Glossary

This glossary contains definitions of those terms and abbreviations that relate specifically to the contents of this book. It also contains terms and definitions from the IBM® Dictionary of Computing, published by McGraw-Hill.

If you do not find the term you are looking for, refer to the Index or to the IBM Dictionary of Computing.

ACB
Access method control block (VTAM®).
ACF/NCP/VS
Advanced Communication Facilities/Network Control Program/Virtual Storage.
ACF/VTAM
Advanced Communication Facilities, Virtual Telecommunications Access Method. A set of programs that control communication between terminals and application programs running under VSE, OS/VS1, and MVS™.
Advanced Program-to-Program Communication (APPC)
The general term chosen for the LUTYPE6.2 protocol under Systems Network Architecture (SNA).
alternate facility
An IRC or SNA session that is obtained by a transaction by means of an ALLOCATE command. Contrast with principal facility.
APPC
Advanced Program-to-Program Communication.
ATI
Automatic transaction initiation.
attach header
In SNA, a function management header that causes a remote process or transaction to be attached.
back-end transaction
In synchronous transaction-to-transaction communication, a transaction that is started by a front-end transaction.
backout
See dynamic transaction backout.
bind
In SNA products, a request to activate a session between two logical units.
CDB
Conversation data block.
central processing complex (CPC)
A single physical processing system, such as the whole of an ES/9000 9021 Model 820, or one physical partition of such a machine. A physical processing system consists of main storage, and one or more central processing units (CPUs), time-of-day (TOD) clocks, and channels, which are in a single configuration. A CPC also includes channel subsystems, service processors, and expanded storage, where installed.
CICSplex
(1) A CICS® complex. A CICSplex consists of two or more regions that are linked using CICS intercommunication facilities. The links can be either intersystem communication (ISC) or multiregion operation (MRO) links, but within a CICSplex are more usually MRO. Typically, a CICSplex has at least one terminal-owning region (TOR), more than one application-owning region (AOR), and may have one or more regions that own the resources that are accessed by the AORs. (2) The largest set of CICS regions or systems to be manipulated by a single CICSplex SM entity.
CICSPlex® System Manager (CICSPlex SM)
An IBM CICS system-management product that provides a single-system image and a single point of control for one or more CICSplexes.
class of service (COS)
An ACF/VTAM facility that allows APPC sessions to have different characteristics to provide a user with alternate routing, mixed traffic, and trunking. Based on their class of service, sessions can take different virtual routes, use different physical links, and be of high or low priority to suit the traffic carried on them.
Common Programming Interface (CPI)
An SAA standard specifying the languages, commands, and calls that can be used in an SAA application program.
conversation
A sequence of exchanges between two transactions over a session, delimited by SNA brackets.
conversation data block
An area used by a program to obtain information about the outcome of a DTP command on an APPC basic conversation.
COS
Class of service.
CPC
Central processing complex.
CPI
Common Programming Interface.
conversation
A sequence of exchanges between transactions over a session, delimited by SNA brackets.
cross-system coupling facility (XCF)
The MVS/ESA cross-system coupling facility provides the services that are needed to join multiple MVS images into a sysplex. XCF services allow authorized programs in a multisystem environment to communicate (send and receive data) with programs in the same, or another, MVS image. Multisystem applications can use the services of XCF, including MVS components and application subsystems (such as CICS), to communicate across a sysplex. See the MVS/ESA Planning: Sysplex Management manual, GC28-1620, for more information about the use of XCF in a sysplex.
data link protocol
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 security
Prevention of access to or use of stored information without authorization.
distributed transaction processing (DTP)
The distribution of processing between transactions that communicate synchronously with one another over intersystem or interregion links.
DL/I
Data Language/I. An IBM database management facility.
DTP
Distributed transaction processing.
dynamic transaction backout
The process of canceling changes made to stored data by a transaction following the failure of that transaction for whatever reason.
EIB
EXEC interface block.
FMH
Function management header.
front-end transaction
In synchronous transaction-to-transaction communication, the transaction that acquires the session to another system and initiates a transaction on that system. Contrast with back-end transaction.
function management header (FMH)
In SNA, one or more headers optionally present in the leading request unit (RU) of an RU chain. It allows one session partner in a LU-LU session to send function management information to the other.
function shipping
The process, transparent to the application program, by which CICS accesses resources when those resources are actually held on another CICS system.
GDS
Generalized data stream.
generalized data stream (GDS)
The data stream used for conversations on APPC sessions.
host computer
The primary or controlling computer in a data communication system.
IMS/VS
Information Management System/Virtual Storage.
inquiry
A request for information from storage.
intercommunication facilities
A generic term covering intersystem communication (ISC) and multiregion operation (MRO).
interregion communication (IRC)
The method by which CICS implements multiregion operation (MRO).
intersystem communication (ISC)
Communication between separate systems by means of SNA networking facilities or by means of the application-to-application facilities of VTAM.
IRC
Interregion communication.
ISC
Intersystem communication.
local resource
In CICS intercommunication, a resource that is owned by the local system.
local system
In CICS intercommunication, the CICS system from whose point of view intercommunication is being discussed.
logical unit (LU)
A port through which a user gains access to the services of a network.
LU
Logical unit.
LU-LU session
A session between two logical units in an SNA network.
modegroup
A VTAM LOGMODE entry which can specify (among other things) the class of service required for a group of APPC sessions.
modename
The name of a modeset.
modeset
A group of APPC sessions specified in CICS.
MRO
Multiregion operation.
multiregion operation (MRO)
Communication between CICS systems without the use of SNA networking facilities. The systems must be in the same operating system; or, if the XCF access method is used, in the same MVS sysplex.
multitasking
Concurrent execution of application programs within a CICS partition or region.
multithreading
Use, by several transactions, of a single copy of an application program.
MVS
Multiple Virtual Storage. An alternative name for OS/VS2 Release 3, or MVS/ESA.
MVS image
A single occurrence of the MVS/ESA operating system that has the ability to process a workload. One MVS image can occupy the whole of a CPC, or one physical partition of a CPC, or one logical partition of a CPC that is operating in PR/SM™ mode.
MVS sysplex
See sysplex.
network
A configuration connecting two or more terminal installations.
network configuration
In SNA, the group of links, nodes, machine features, devices, and programs that make up a data processing system, a network, or a communication system.
Operating System/Virtual Storage (OS/VS)
A compatible extension of the IBM System/360 Operating System that supports relocation hardware and the extended control facilities of System/360.
OS/VS
Operating System/Virtual Storage.
PIP
Program initialization parameters.
principal facility
The terminal or logical unit that is connected to a transaction at its initiation. Contrast with alternate facility.
program initialization parameters (PIP)
Specially formatted data passed to a back-end transaction with the CONNECT PROCESS command.
queue
A line or list formed by items in a system waiting for service; for example, tasks to be performed or messages to be transmitted in a message-switching system.
RACF®
The Resource Access Control Facility program product. An external security management facility.
region
A section of the dynamic area that is allocated to a job step or system task. In this manual, the term is used to cover partitions and address spaces in addition to regions.
remote resource
In CICS intercommunication, a resource that is owned by a remote system.
remote system
In CICS intercommunication, a system that the local CICS system accesses via intersystem communication or multiregion operation.
resource
Any facility of the computing system or operating system required by a job or task, and including main storage, input/output devices, the processing unit, data sets, and control or processing programs.
rollback
A programmed return to a prior checkpoint. In CICS, the cancelation by an application program of the changes it has made to all recoverable resources during the current unit of work.
RU
Request/response unit. In SNA, the basic unit of information entering or leaving the transmission subsystem. It may contain data, acknowledgements, control commands, or responses to commands.
SAA
Systems Application Architecture®.
security
Prevention of access to or use of data or programs without authorization.
session
In CICS intersystem communication, an SNA LU-LU session.
SNA
Systems Network Architecture.
subsystem
A secondary or subordinate system.
synchronization level
The level of synchronization (0, 1, or 2) established for an APPC session.
syncpoint
Synchronization point. During transaction processing, a reference point to which protected resources can be restored if a failure occurs.
sync level
synchronization level.
sysplex
A systems complex, consisting of multiple MVS images coupled together by hardware elements and software services. When multiple MVS images are coupled using XCF, which provides the services to form a sysplex, they can be viewed as a single entity.
system
In CICS, an assembly of hardware and software capable of providing the facilities of CICS for a particular installation.
Systems Application Architecture (SAA)
A set of common standards and procedures for working with IBM systems and data.
Systems Network Architecture (SNA)
The description of the logical structure, formats, protocols, and operational sequences for transmitting information units through, and controlling the configuration and operation of, networks. The structure of SNA allows the end users to be independent of, and unaffected by, the specific facilities used for information exchange.
task
(1) A unit of work for the processor; therefore the basic multiprogramming unit under the control program. (CICS runs as a task under VSE, OS/VS, MVS, or MVS/ESA.) (2) Under CICS, the execution of a transaction for a particular user. Contrast with transaction.
TCT
Terminal control table.
temporary storage control
The CICS element that provides temporary data storage facilities.
temporary storage table
A table describing temporary storage queues and queue prefixes for which CICS is to provide recovery.
terminal
In CICS, a device equipped with a keyboard and some kind of display, capable of sending and receiving information over a communication channel.
terminal control
The CICS element that controls all CICS terminal activity.
terminal control table (TCT)
A table describing a configuration of terminals, logical units, or other CICS systems in a CICS network with which the CICS system can communicate.
terminal operator
The user of a terminal.
transaction
A transaction can be regarded as a unit of processing (consisting of one or more application programs) initiated by a single request, often from a terminal. A transaction may require the initiation of one or more tasks for its execution. Contrast with task.
transaction backout
The cancelation, as a result of a transaction failure, of all updates performed by a task.
transaction identifier
Synonym for transaction name. For example, a group of up to four characters entered by an operator when selecting a transaction.
transaction restart
The restart of a task after a transaction backout.
transaction routing
A CICS facility that allows terminals or logical units connected to one CICS region to initiate and to communicate with transactions in another CICS region within the same processor system or in another CICS system connected by an APPC link.
transient data control
The CICS element that controls sequential data files and intrapartition data.
unit of work (UOW)
A sequence of actions that can be regarded as logically-related for the purposes of CICS error recovery mechanisms.
UOW
Unit of work.
VTAM
See ACF/VTAM.
XCF
Cross-system coupling facility.
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