- daisy chain
- In CICS intercommunication, the chain of sessions that results
when a system requests a resource in a remote system, but the remote system
discovers that the resource is in a third system and has itself to make a
remote request.
- DASD
- See direct access storage device (DASD).
- DASD sharing
- An option that lets independent computer systems use common data on
shared disk devices.
- data aggregate
- A group of data elements
that describe a particular entity.
- data availability
- An IMS enhancement available with DBCTL. It allows PSB scheduling to complete
successfully even if some of the full-function databases it requires are not
available.
- database (DB)
- A collection of interrelated or independent data
items stored together without redundancy to serve one or more applications.
- Database Control (DBCTL)
- An interface between CICS Transaction
Server and IMS/ESA that allows access to IMS DL/I full-function databases
and to data entry databases (DEDBs) from one or more CICS systems without
the need for data sharing. It also provides release independence, virtual
storage constraint relief, operational flexibility, and failure isolation.
- database description (DBD)
- The collection of macroparameter statements
that define the characteristics of a database, such as the database's organization
and access method, the segments and fields in a database record, and the relationship
between types of segments.
- database integrity
- The protection
of data items in a database while they are available to any application program.
This includes the isolation of effects of concurrent updates to a database
by two or more application programs.
- database-level sharing
- A kind of data sharing that enables application programs in one
IMS subsystem to read data while another program in another IMS subsystem
reads from the same database or updates it. In IMS data sharing, a CCS system
can be an IMS subsystem. See also block-level data sharing.
- database
organization
- The physical arrangement of related data on a storage
device. DL/I database organizations are hierarchical direct (HD) and hierarchical
sequential (HS).
- database program communication
block (DBPCB)
- The PCB that describes an application program's
interface to a database. One DBPCB is required for each database view used
by the application program.
- database record
- In a DL/I, IMS or SQL/DS
database, a collection of segments that contains one occurrence of the root
segment type and all of its dependents arranged in a hierarchical sequence.
It may be smaller than, equal to, or larger than the access method logical
record.
- database recovery
- The function of restoring the user data sets,
starting with a backup copy and applying all changes made to each data set
after the backup was taken.
- database recovery control (DBRC)
- An IMS facility that maintains information needed for database
recovery, generates recovery control statements, verifies recovery input,
maintains a separate change log for database data sets, and supports the sharing
of an IMS DL/I database by multiple subsystems. In IMS data sharing, a subsystem
can be an IMS region or a CICS region.
- database reorganization
- The process of unloading and reloading a database to optimize
physical segment adjacency, or to modify the DBD.
- database resource adapter (DRA)
- Component of the CICS-DBCTL interface
in the CICS address space. Its functions include requesting connection and
disconnection from DBCTL, telling CICS when a shutdown of DBCTL has been requested
or if DBCTL has failed, managing threads, establishing contact with the DBCTL
address space, and loading the DRA startup parameter table.
- Data Cache
Manager
- A component of CICSPlex SM that manages logical cache
storage for use by other CICSPlex SM components.
- data-container
- A named area of storage, maintained by BTS, and used to pass
data between activities, or between different invocations of the same activity.
Each data-container is associated with an activity; it is identified by its
name and by the activity for which it is a container. An activity can have
any number of containers, as long as they all have different names. See also process container.
- data control block (DCB)
- A control block used by access method routines in storing and retrieving data.
- data definition name (ddname)
- The name of a data definition
(DD) statement that corresponds to a data control block that contains the
same name.
- data element
- (1) A unit of data that, in certain context, is considered
indivisible. For example, the data element "age of a person" with values consisting
of all three-decimal digit combinations. (T)
- (2) The smallest unit
of data that can be referred to.
- data entry database (DEDB)
- A direct-access database that consists of one or more areas,
with each area containing both root segments and dependent segments. The database
is accessed using VSAM media manager.
- data independence
- In CICS, the ability to request data by a high-level data-management method
without concern as to how the data is stored or retrieved.
- data interchange block (DIB)
- A block created by the CICS data
interchange program (DIP) to control input and output to SNA batch devices.
The DIB is chained to the appropriate TCTTE for the batch device, and is released
at the termination of the transaction.
- data interchange
program (DIP)
- A CICS program that communicates with batch data
interchange terminals, such as the 3790, for bulk transfer of dumps, data
sets, and so on.
- Data Interfile
Transfer, Testing and Operations (DITTO) utility
- An IBM licensed
program that provides file-to-file services for card I/O, tape, and disk devices.
- Data Language/I (DL/I)
- The IMS data manipulation language, a common
high-level interface between a user application and IMS. DL/I calls are invoked
from application programs written in languages such as PL/I, COBOL, VS Pascal,
C, and Ada. It can also be invoked from assembler language application programs
by subroutine calls. IMS lets the user define data structures, relate structures
to the application, load structures, and reorganize structures.
- data link protocol
- In SNA, a set of rules for data communication over a data link
in terms of a transmission code, a transmission mode, and control and recovery
procedures.
- data management block (DMB)
- An IMS control block in main storage
that describes and controls a physical database. It is constructed from information
obtained from the ACB library or the DBD library.
- data-owning
region (DOR)
- A CICS address space whose primary purpose is to
manage files and databases. See application-owning region (AOR), and terminal-owning region (TOR).
- data repository
- A component of CICSPlex SM that provides methods
for creating, accessing, updating, and deleting data in the CICSPlex SM data
repository.
- data security
- The protection of data against unauthorized disclosure,
transfer, modification, or destruction, whether accidental or intentional.
- data set
- The major unit of data storage and retrieval, consisting
of a collection of data in one of several prescribed arrangements, and described
by control information to which the system has access.
- data set name block (DSNAME block, DSNB)
- An area, addressed by
a FCT entry, that represents a physical VSAM or BDAM (DAM in CICS/VSE) data
set that is being accessed through one or more CICS files. A DSNAME block
(DSNB) is created, if it does not already exist, when a file is opened or,
in CICS Transaction Server only, when a SET FILE DSNAME command is executed.
- data set name sharing
- An MVS or VSE option that allows one set
of control blocks to be used for the base and the path in a VSAM alternate
index.
- data set profile
- A RACF profile that provides protection for one
or more data sets. The information in the profile can include the data set
profile name, profile owner, universal access authority, access list, and
other data. See profile, discrete profile and generic profile.
- data space
- A range of up to two gigabytes of contiguous virtual
storage addresses that a program can directly manipulate. Unlike an address
space, a data space can hold only data; it does not contain common areas or
system data or programs. See also address space.
- data stream
- All information (data and control commands) sent over a data
link usually in a single read or write operation. For example, a data stream
is used to send displays and to receive displays from a workstation device.
- data table
- A file whose records are held in main storage. See
also CICS-maintained data table (CMT) and user-maintained data table (UMT).
- DB
- See database.
- DB2
- A family of IBM licensed programs for relational database
management.
- DBCS
- See double-byte character set (DBCS).
- DBCTL
- See Database Control (DBCTL).
- DBD
- See database description (DBD).
- DBO
- See DL/I backout table (DBO).
- DBPCB
- See database program communication block (DBPCB).
- DBRC
- See database recovery control (DBRC).
- DCB
- See data control block (DCB).
- DDEP
- Direct dependent
segment in a DEDB.
- DDIR
- See DL/I database directory (DDIR).
- DDMMYYYY
- Day-day-month-month-year-year format of a date (for example, 14022001
for 14 February 2001). This is the default format for the DATFORM system initialization
parameter.
- ddname
- See data definition name (ddname).
- deadlock
- (1) Unresolved contention
for the use of a resource.
- (2) An error condition in which processing
cannot continue because each of two elements of the process is waiting for
an action by, or a response from, the other.
- deblocking
- The process
of removing each logical record from a block. See also blocking.
- debugging client
- A program that runs
on a workstation and is used to debug a CICS application program.
- debugging profile
- Data that specifies a set of application programs
which are to be debugged together. See also profile.
- DEDB
- See data entry database (DEDB).
- default group
- In RACF, the group specified in a user profile that is the default current
connect group.
- default user
- The user whose security attributes are used to protect
CICS resources in the absence of other, more specific, user identification.
For example, except in the case of terminals defined with preset security,
the security attributes of the default user are assigned to terminal users
who do not sign on.
- default user ID
- The user identifier (userid) of
the default user. The default user ID is specified with the DFLTUSER
system initialization parameter.
- deferred work element
(DWE)
- A work element created and placed on a chain (the DWE chain)
to save information about an event that must be completed before task termination
but that is not completed at the present time. DWEs are also used to save
information about work to be backed out in case of an abend.
- defined
userid
- A user identifier (userid) named on a DEFINE PROCESS or
DEFINE ACTIVITY command. It specifies the userid under whose authority the process or activity will be
run, if it is activated by a RUN command. If the process or activity is activated
by a LINK command, it runs under the authority of the userid of the transaction
that issues the LINK.
- define the file (DTF)
- The DTF
is a DAM control block that identifies to DAM the file associated with this
DAM request. It is passed to DAM by DFHFCD to initiate a DAM request, and
lasts for the lifetime of the CICS run. The DTF is included in the associated
FCT entry, and is generated at FCT assembly time by the DTFDA macro. There
is one DTF per DAM FCT entry.
- definite response (DR)
- In SNA, a value in the response-requested field of the request
header that directs the receiver of the request to return a response unconditionally,
whether positive or negative, to that request. See also exception response (EX, ER), no response.
- delegation
- In RACF, the act of giving other
users or groups authorities to perform RACF operations.
- delete lock
- Lock acquired by CICS file control whenever a DELETE, WRITE, or WRITE
MASSINSERT operation is being performed for a recoverable VSAM KSDS or a recoverable
path over a KSDS.
- dependent default
- Attribute value
for RDO that differs depending on the values for the other attributes that
have already been specified on the command line.
- dependent region
- In a multi-MVS or VSE MRO XRF configuration, a region that receives
commands from a master or coordinator region at takeover time. It cannot initiate
a takeover.
- deployed JAR file
- A generic term for a file produced from the
ejb-jar file. It contains the XML deployment descriptor and enterprise bean
classes from the ejb-jar file, plus additional classes generated to support
the chosen EJB container. See also CICS-deployed JAR file.
- deployed
security role
- A security role that is qualified with the display
name specified in an enterprise bean's deployment descriptor, and the prefix
specified in the EJBROLEPRFX system initialization parameter. See security role and deployment descriptor. For more information see Java(TM)
applications in CICS.
- deployment
- The act of packaging enterprise
beans into a JAR file for distribution to a container on an enterprise bean
server.
- deployment descriptor
- An XML file that describes how a module
or application should be deployed, by specifying configuration and container
options. For example, an EJB deployment descriptor passes information to an
EJB container about how to manage and control an enterprise bean. See also deployed security role.
- destination
- A queue of data used with the
CICS transient data facility.
- destination control table
- A table describing each of the transient data destinations used
in CICS. This table contains an entry for each extrapartition, intrapartition,
and indirect destination.
- device dependence
- The reliance
on the characteristics of particular types of devices used in writing and
running programs or in performing functions. See also device independence.
- device independence
- The capability to write and run programs or
perform functions without regard for the physical characteristics of devices.
See also device dependence.
- device message handler
(DMH)
- For CICS with TCAM SNA, the logical unit in SNA terms. All
data flow, control, session startup and takedown, and response handling are
provided in the DMH.
- DFH
- Three-character prefix of all CICS modules.
- DIB
- See data interchange block (DIB) and DL/I interface block (DIB).
- dictionary data section
- One of the data sections of a CICS monitoring
record written to SMF. The dictionary data section defines all the performance
data that is being gathered or can be gathered during this CICS run.
- DIP
- See data interchange program (DIP).
- direct access
- A method
for retrieval or storage of a VSAM data record that is independent of the
record's location relative to the previously retrieved or stored data. See
also sequential access.
- direct access method
- An access method used to retrieve or update particular blocks of a data set
on a direct access device.
- direct access storage device
(DASD)
- A storage device that provides direct access to data.
- directory manager domain
- A CICS domain that provides resource-table
lookup services for CICS Transaction Server for z/OS components such as transaction
manager, program manager, and user domains. The resource definitions for which
the directory manager domain provides services are transaction definitions,
remote transaction definitions, transaction classes, TPNames, user attributes,
programs, BMS mapsets, and BMS partition sets.
- dirty read
- A read request
that does not involve any locking mechanism, and which may obtain invalid
data - that is, data that has been updated, but is not yet committed, by another
task. This could also apply to data that is about to be updated, and which
will be invalid by the time the reading task has completed.See also read integrity.
- discrete profile
- A resource profile
that can provide RACF protection for only a single resource. For example,
a discrete profile can protect only a single data set or minidisk. See also data set profile, generic profile, resource profile.
- DISOSS
- See Distributed Office Support System (DISOSS).
- dispatch
- (1) To allocate processing time on a
specific device for a job that is ready to run.
- (2) In CICS, to schedule
a task for execution. Dispatching is done by CICS task control. See also service request block (SRB).
- dispatcher domain
- Major component
of CICS concerned with attaching, running, and detaching tasks and scheduling
task control blocks for the various modes: quasi reentrant, resource-owning,
or concurrent.
- dispatching priority
- A number assigned to tasks, used to determine
the order in which they are to use the processor in the CICS multitasking
environment.
- disposition
- A means of indicating to VSE/POWER how job input and
output is to be handled. A job may, for example, be deleted or kept after
processing.
- distributed application
- An
application whose component programs run on two or more CICS regions.
- distributed data
- Data that is stored on more than one system and
is available to remote users and application programs.
- Distributed Office Support System (DISOSS)
- An IBM office systems
product that helps CICS form the hub for storage, retrieval, and forwarding
of documents among various office systems products.
- distributed processing
- Processing in which resources or functions
are dispersed among two or more interconnected processors, typically over
a network.
- Distributed Processing Control Executive (DPCX)
- An IBM licensed
program that controls the IBM 8100 Information System.
- distributed program link (DPL)
- A function of CICS intersystem
communication that enables an application program to ship LINK requests to
another application program on a different instance of CICS.
- distributed routing model
- A "peer-to-peer" dynamic routing system,
in which each of the participating CICS regions can be both a routing region and a target region. The distributed routing
model is implemented by the distributed routing program.
- distributed routing program
- A CICS-supplied user-replaceable program
that can be used to dynamically route; BTS processes and activities, and Transactions
started by non-terminal-related EXEC CICS START commands.
- distributed transaction processing (DTP)
- A process that enables
a CICS transaction to communicate synchronously with a transaction running
in another instance of CICS.
- distributed unit of
work (DUW)
- In a distributed process, all processing between two
syncpoints taken by two or more intercommunicating transactions using a two-phase
commit protocol. A DUW is a distributed LUW.
- distribution zone
- In SMP/E, a group of VSAM records that describe the structure and contents
(that is, the SYSMODs and elements) of a set of distribution libraries.
- DITTO utility
- See Data Interfile Transfer, Testing and Operations.
- DJAR
- A CICS resource
definition that defines a CICS-deployed JAR file. It is not a deployed JAR
file itself.
- DLBL statement
- Data definition statement in VSE JCL. A DLBL statement
specifies the name and characteristics of a data set to be associated with
a file definition in the FCT. The name of the DLBL statement is the same as
the name of the file definition.
- DL/I
- See Data Language/I (DL/I).
- DL/I backout table (DBO)
- In the restart data set, a summary table
that contains an entry for each in-flight task that was scheduled to alter
a local DL/I database. Data in this table is available to user-written exit
programs.
- DL/I database directory (DDIR)
- List of data management blocks
(DMBs) that define for DL/I the physical and logical characteristics of databases.
- DL/I interface block (DIB)
- A block containing variables automatically
defined in an application program using HLPI to receive information passed
to the program by DL/I during execution. A block automatically inserted into
a program by the DLI command translator. Whenever a program issues an EXEC
DLI request, DLI responds by storing information in the DIB.
- DLISAS
- See DLI separate address space (DLISAS).
- DLI separate address space
(DLISAS)
- A component of DBCTL that resides in the IMS address
space. It is a separate address space that contains DL/I code, control blocks,
buffers for DL/I databases and program isolation. See CICS-IMS DBCTL environmentfor more information.
- DMB
- See data management block (DMB).
- DMH
- See device message handler (DMH).
- document
- A logical structure that a CICS transaction can use to manipulate text or
other structured information. For more information, see CICS Application Programming Guide.
- document template
- A unit of information that is used to construct a document.
A document template can contain fixed text, and symbols that represent text
whose value is supplied by an application program. Document templates can
be created by a CICS application, or retrieved from an external source. For
more information, see CICS Application Programming Guide.
- domain
- A functionally isolated area of the CICS system that owns
resources to which it has sole access and that communicates with other parts
of CICS through strictly defined interfaces called gates.
- domain gate
- An entry point or interface to a CICS domain. A domain gate can be called
by any authorized caller who needs to use some function provided by the domain.
- domain manager domain
- Major component of CICS responsible for
maintaining, through the use of catalog services, permanent information about
individual domains.
- Domain Name System (DNS)
- In the Internet suite of protocols, the distributed database system used to
map domain names to IP addresses.
- DOR
- See data-owning region (DOR).
- double-byte character set (DBCS)
- A set of characters in which
each character is represented by two bytes. These character sets are commonly
used by national languages, such as Japanese and Chinese, that have more symbols
than can be represented by a single byte. See also single-byte character set.
- DPCX
- See Distributed Processing Control Executive (DPCX).
- DPL
- See distributed program link (DPL).
- DR
- See definite response (DR).
- DRA
- See database resource adapter (DRA).
- DRA control exit
- Enables the DRA to pass information from itself
and DBCTL independently of CICS. It is invoked whenever the DRA needs to determine
whether to continue processing.
- DRA startup parameter
table
- Provides the parameters needed to define a DBCTL subsystem.
- DRx response
- See definite response (DR).
- DSA
- See dynamic storage area (DSA).
- DSNAME block
- See data set name block (DSNAME block or DSNB).
- DSNB
- See data set name block (DSNAME block or DSNB).
- DTB
- See dynamic transaction backout (DTB).
- DTF
- See define the file (DTF).
- DTP
- See distributed transaction processing (DTP).
- DTR
- See dynamic transaction routing (DTR).
- dual-purpose
definition
- For transaction routing or function shipping, a means
of sharing file, terminal, or transaction definitions between systems. For
further information, see Dual-purpose resource definition
for transient data.
- dual-screen
- Running EDF and the transaction
to be tested on different terminals.
- dump
- A representation of the
contents of selected areas of main storage used to find out whether a program
is functioning as intended and to analyze problems. Dumps may be recorded
by CICS either as a consequence of failure detected during CICS execution,
or upon explicit request. See also partition dump, system dump (IDUMP),
and transaction dump.
- dump code
- (1) In CICS Transaction Server, a predefined
name by which a dump is known. There are two types of dump code, transaction
dump codes and system dump codes, used in transaction dumps and system dumps,
respectively. A dump code can be defined by CICS or the user and is used to
select a set of system actions. These actions are held in either the system
or transaction dump table See also system dump code, system dump table entry, transaction dump code, transaction dump table (TDT).
- (2) In CICS/VSE, a predefined
name by which a transaction dump is known. The VSE/ESA Messages and Codes manual contains a description of the transaction dump
codes defined by CICS.
- dump data set
- A sequential data set (optional)
used to record dumps of transactions (tasks) within the system. It can be
formatted and printed by the CICS dump utility program (DFHDUP). If required,
the user can define two dump data sets (DFHDMPA and DFHDMPB), switching between
them during online execution of CICS.
- dump domain
- Major component
of CICS responsible for producing storage dumps and for handling the associated
data sets and dump tables.
- dump table
- A table of dump codes to enable
a user to vary the system actions taken when a dump is produced for a particular
dump code. There are two dump tables - one containing system dump codes for
system dump requests, and one containing transaction dump codes for transaction
dump requests. Dump tables are internally maintained by CICS, but cannot be
externally generated like CICS control tables. There are two dump tables -
one containing system dump codes for system dump requests, and one containing
transaction dump codes for transaction dump requests. Dump tables are internally
maintained by CICS, but cannot be externally generated like CICS control tables.
- dump utility program (DFHDUP)
- An offline utility program that
formats and prints the output from formatted dump, and prints transaction
dumps. It operates in batch mode and, for formatted dumps, identifies each
storage area, program, and table entry, and prints them separately, with actual
and relative addresses.
- durability
- After a transaction
completes successfully (commits), its changes to the state survive failures.
See also ACID properties.
- DUW
- See distributed unit of work (DUW).
- DWE
- See deferred work element (DWE).
- dynamic allocation
- Facility of IMS Version 2.2 (or later) and of CICS Transaction Server,
for allocating DL/I databases and CICS file control data sets, respectively.
If no DD statement is provided for the database data sets contained in the
database, allocation happens automatically when the database is scheduled.
- dynamically loaded program
- Program loaded into a dynamic storage
area as required by a task.
- dynamic backout
- A process that automatically
cancels all activities performed by an application program that terminates
abnormally. See also backout and syncpoint.
- dynamic buffer
- Used to store backout information in the dynamic
log for dynamic transaction backout (DTB) purposes. The dynamic buffer is
not acquired until a recoverable resource has been modified. If dynamic backout
is not defined for a transaction, the dynamic buffer is not used.
- dynamic log
- An area in main storage used (by the journal control program) for storing
copies of all changes to recoverable resources that might be required for
dynamic backout of an LUW. Every execution of a transaction that has dynamic
transaction backout specified has an associated dynamic log area.
- dynamic parse
- A method of parsing TSO commands according to syntax given in an external
file.
- dynamic partition
- A partition configured at the time of program
execution according to the storage requirements of the application program
or program to which the partition is allocated.
- dynamic partition
balancing
- A VSE facility that allows the user to specify that
two or more or all partitions of the system should receive about the same
amount of time on the processing unit.
- dynamic routing
- The automatic routing of a transaction or program, at the time it is initiated,
from a requesting region to a suitable target region. Routing terminal data
to an alternative transaction at the time the transaction is invoked. To do
this, CICS allows the dynamic routing program to intercept the terminal data
and redirect it to any system and transaction it chooses.
- dynamic routing model
- The "traditional", hierarchical CICS dynamic
routing system, in which a single terminal-owning region (the routing region)
routes transactions between several application-owning regions (the target regions). The dynamic routing model is implemented by the dynamic
routing program.
- dynamic routing program
- A user-replaceable
CICS program that selects dynamically both the system to which a request is
to be sent and the transaction's remote name. The alternative to using this
program is to make these selections when a remote transaction is defined to
CICS (static routing).
- dynamic storage
- An area of storage
that is explicitly allocated by a program or procedure while it is running.
See also auxiliary storage.
- dynamic storage area (DSA)
- In CICS Transaction Server, there are five dynamic storage areas.
These are CICS and user areas below the 16MB line, CICS and user above the
16MB line, and an extended read only area above the 16MB line. CICS DSAs are
preallocated at system initialization. CICS DSAs are preallocated at system
initialization as specified by a series of system initialization parameters,
CDSASZE, UDSASZE, ECDSASZE, ERDSASZE, and EUDSASZE.
- dynamic transaction backout (DTB)
- The process of canceling changes
made by a transaction to recoverable resources following a failure of the
transaction for whatever reason.
- dynamic transaction
routing (DTR)
- The automatic routing of a transaction, at the time
it is initiated, from a transaction-owning region (TOR) to a suitable application-owning
region (AOR).
- dynamic transaction routing program (DFHDYP)
- A user-replaceable
CICS program that selects dynamically both the system to which a transaction
routing request is to be sent and the transaction's remote name. The alternative
to using this program is to make these selections when a remote transaction
is defined to CICS (static transaction routing). For programming information,
see Writing a dynamic routing program.
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