gtpd3m0fLibrary Guide with Master Index and Glossary

C

cache
A random access electronic storage medium in selected storage controllers used to retain data for faster access by the channel.

cache fast write (CFW)
A form of fast write where the data is written directly to cache without using nonvolatile storage and is available for later destaging. The data is not placed on the DASD surface until a destage is performed.

cache fast write duplex (CFWD)
A user-specified caching attribute that allows a data record to be written as cache fast write data to both the prime and duplicate modules. All read operations are queued to the prime module. Access to data with this attribute has performance benefits for both read and write errors. This attribute is specified for a given record ID through the RIAT.

cache fast write identifier (CFWID)
An identification used to insure that a channel program does not access data in a cache that is downlevel.

cache fast write simplex (CFWS)
A user-specified caching attribute that allows a data record to be written as cache fast write data to the prime module only of a TPF prime and duplicate module pair. All read operations are queued to the prime module. Access to data with this attribute has performance benefits for both read and write errors. This attribute is specified for a given record ID through the RIAT.

cache fast write identifier
See CFWID.

cache fast write simplex
See CFWS attribute.

cache structure
See coupling facility cache structure.

canned message
In earlier TPF applications, the term given to output messages in which text is predefined and restricted to 13 characters.

capture
The utility that copies online storage to 2 sets of logical tapes: one set contains online files as they exist at the moment of capture; a second set, the exception tapes, collects a copy of any record that was altered after it was captured. Together, these tapes contain a static copy of the database as it existed at the time the capture utility completed processing.

capture/restore
See capture and restore.

case clause
In a switch statement, a case label followed by any number of statements.

case label
The word case followed by a constant expression and a colon.

cast
An expression that converts the type of the operand to a specified scalar data type (the operator).

catastrophic error
A system error that forces processing to end and necessitates a re-IPL of the TPF system.

catch block
A block associated with a try block that receives control when an exception matching its argument is thrown.

CBRW
Core block reference word.

CCB
Conversation control block.

CC code
Each CodesetRegistry-CodesetEncoding name is assigned a 2 character name. If the first byte of the CC code is a letter then it is reserved for IBM.

CCCTIN
A control program CSECT handling key main storage initialization procedures. Also called the initializer program.

CCP
Communications control program.

CCSID
A CCSID is a number from 0 to 65535 that describes how character data is represented on a machine. A single CCSID will describe 3 major features of a machines character data: ESID, Code Set number Code Page number. In many cases but not all, CCSID = Code Page number.

CCT
Common frame control table.

CDC
Continuous data collection.

CDT
CLAW device table.

central processing unit (CPU)
The part of a computer that includes the circuits that control the interpretation and execution of instructions.
Note:
A CPU is the circuitry and storage that executes instructions. The centrality of a processor or processing unit depends on the configuration of the system or network in which it is used.

central processor complex (CPC)
(1) A configuration that consists of all the machines required for operation. See processor complex. (2) A system configuration consisting of main storage, one or more CPUs, and a channel subsystem containing logical subchannels and channel paths. Main storage in one CPC is not directly accessible by the CPUs and channel subsystem of another CPC. Not all I-stream engines of a CPC will necessarily be logically enabled to access the devices attached to the channel subsystem.

centralized list handling (CLH)
A set of centralized routines used for dispatching system tasks.

C function trace
Enables ISO-C programs compiled using the TEST option of the compiler to trace information on entry to, exit from, and within C functions, dynamic load modules (DLMs), and C library functions.

CFCB
Coupling facility connection block.

CFCT
Coupling facility control table.

CFLF
Concurrency filter lock facility.

CFRB
Coupling facility request block.

CFSB
Coupling facility structure block.

CFST
Coupling facility status table.

CFTT
Coupling facility trace table.

C function trace
Enables ISO-C programs compiled using the TEST option of the compiler to trace information on entry to, exit from, and within C functions, dynamic load modules (DLMs), and C library functions.

CFVB
Coupling facility vector block.

CFW
Cache fast write.

CFWD
Cache fast write duplex.

CFWID
Cache fast write identifier.

CFWS
Cache fast write simplex.

chain chasing
The act of accessing every fixed record and main storage table that might refer to pool records and, in turn, reading those records and any more pool records referred from them. The phase during recoup when defined record chains are read to determine pool usage.

change number of sessions (CNOS)
TPF/APPC verbs that are used to change the (LU,mode) session limit. This session limit controls the number of LU-LU sessions per mode name that are available between two LU 6.2 types for allocation to conversations.

char specifier
The words char or unsigned char, which describe the type of data a variable represents.

character constant
A character or an escape sequence enclosed in single quotation marks.

character set
(1) A group of symbols shown on a terminal. A character set used in the USA might have the letters A-Z in both capital and small. A character set used in Japan, however, might have Katakana characters instead. (2) A group of characters used for a specific reason; for example, the set of characters a printer can print or a keyboard can support.

character translation table
An item that has a 1 for 1 character mapping from one code page to another code page.

character variable
A data object whose value can be changed during program execution and whose data type is char or unsigned char.

checkpoint
(1) A time when significant information is written on the log. (2) In MQSeries on UNIX systems, the point in time when a data record described in the log is the same as the data record in the queue. Checkpoints are generated automatically and are used during the system restart process.

child process
A process that is created by a parent process. See also parent process and process.

child server
Transmission Control Protocol/Internet Protocol (TCP/IP) support provides the activate_on_receipt function, which defines a new program called the child server program. The child program is activated when an incoming message arrives from a client.

CID
TPF C implementation data.

CIMR area
Core image restart area.

CINFC tag
The symbolic name of a main storage resident system table.

CIO
Common input/output (I/O).

C language
A general-purpose high-level programming language.

class
A C++ aggregate that can contain members such as functions, types, and user-defined operators in addition to data. A class can be defined hierarchically, allowing one class to be derived from another, and can restrict access to its members. A user-defined data type. A class data type can contain both data representations (data members) and functions (member functions). The internal representation of a collection implementation. See object class.

class ID
An identifier in the object header that indicates the most detailed classification of the object.

CLAW
Common Link Access to Workstation.

CLAW API
The application programming interface that provides restricted ISO-C interface functions to communicate with any CLAW workstation, such as the TCP/IP offload device.

CLAW device interface
See TPF CLAW device interface.

CLAW device table (CDT)
A control block structure located in main storage in the TPF system. It contains information about each CLAW device defined in the system.

CLAW host application
An application on a TPF host processor that is used to establish a Common Link Access to Workstation (CLAW) connection with an application on a CLAW workstation.

CLAW host name
A name assigned to a TPF host processor that is used by a CLAW workstation to identify that TPF host processor.

CLAW protocol
Common Link Access to Workstation protocol.

CLAW workstation
A device that communicates with the TPF system using the Common Link Access to Workstation (CLAW) protocol. The IBM 3172 Model 3 Interconnect Controller is an example of a CLAW workstation.

CLAW workstation application
An application on a CLAW workstation that is used to establish a Common Link Access to Workstation (CLAW) connection with a CLAW host application on a TPF host processor.

CLH
Centralized list handling.

client
In TCP/IP, a program at one site requesting services from a program at another site. See also server.

C load module
A type of load module. For historical reasons, load modules on the TPF system were referred to as C load modules.

CLU
Control point logical unit.

CMC
Communications management configuration.

CNOS
Change number of sessions.

Code Page
For every value of a character byte, (00 to FF or 0 to 255) there is a unique meaning. The definition of all 255 possible characters is known as its code page.

Codeset Name
See CodesetRegistry-CodesetEncoding name.

Codeset Name Conversion Table
A table that provides conversions from codeset name to CC code.

CodesetRegistry-CodesetEncoding name
A code page number might be 500 or 1047. IBM will give it a name such as IBM-500 or IBM-1047. Names prefixed with IBM- are supported by IBM.

collection
The primary entity in TPF collection support (TPFCS).. A collection consists of a related group of elements organized within a data store. Collections are created by applications and can be temporary or persistent.

collection parts
See collection part objects.

collection part objects
In TPF collection support (TPFCS), objects used to represent the same collection that are unrelated in terms of inheritance.

COMM SOURCE
Communication source program.

comma expression
An expression that contains two operands separated by a comma. Although the compiler evaluates both operands, the value of the right operand is the value of the expression. If the left operand produces a value, the compiler discards this value.

command
(1) A request to perform an operation or run a program. When parameters, arguments, flags, or other operands are associated with a command, the resulting character string is a single command. (2) Operator messages, accepted only from CRAS terminals, that are used to communicate with the control program to request services or modify system parameters. They are sometimes called functional messages or Z-messages because the first character of the message is always Z.

comment
A comment contains text that the compiler ignores. Comments begin with the /* characters, end with the */ characters, and span any number of lines. Comments cannot be nested.

commit
In TPF transaction services, to apply all of the file changes that were made inside of a commit scope.

commit scope
A unit of work that groups together a set of database updates.

common block
A TPF block that is allocated within a common frame. A common block is visible to all ECBs at the same address.

common frame
4KB of storage that are allocated in the pool of storage that is visible to all ECBs at the same address.

common frame control table (CCT)
A control table that keeps track of which common frames are in use, what block type they are being used for, and the ECB that obtained the block.

common I/O (CIO)
A TPF control program routine that manages I/O operations through a macro interface that permits the set of CIO macros supporting each I/O function to make use of a centralized service structure. See also preemptive input/output (PIO).

common I/O handler
The first-level I/O interrupt handler. It saves the current environment, passes control to the appropriate device handler, and performs I/O initiation in response to requests from the control program.

Common Link Access to Workstation (CLAW) protocol
Input/output (I/O) protocol that provides interactive interfaces to workstations. This set of functions is provided through C functions. In the TPF system, CLAW interfaces are restricted interfaces provided by the system and not written by users.

common symbol table
In expression enhancements for the TPF debuggers, a table that contains symbols that are considered common to real-time assembler programs. Use of the common symbol table eliminates the need for multiple copies of the DSECT and symbol information for each real-time assembler program being retained and loaded to the TPF system. Instead, only one copy of the common DSECTs or symbols is kept in the TPF system. You use the common symbol table user exit (UCST) to add the DSECTs and symbols to the table.

communication domain
A name space or an address space that shares common communication properties, such as naming conventions and protocol address formats.

communication macros and statements
Macros or statements used in applications or programs that use any of the various aspects of TPF communications support.

communication source program (COMM SOURCE)
The first ECB-controlled program to be given control for routing input messages to the intended destination.

communications control program (CCP)
The system program that controls all non-SNA communication between external users of the system and the application programs.

communications management configuration (CMC)
The networking configuration where a single host, known as a CMC host node, owns and manages all network resources except those resources that are channel-attached to data hosts in the network. In a TPF environment, VTAM acts as the CMC host node and TPF is a data host node. The term CMC is often used interchangeably with VTAM.

compact resident
A description for a collection in which TPF collection support (TPFCS) stores data using a compact structure. See also compact structure.

compact structure
An object that contains both the actual data elements that an application has stored in a collection, as well as control information that TPF collection support (TPFCS) uses to sort or retrieve those elements. The MemKey object of the StructureMem class is just one example of several kinds of compact structures.

compilation time
The time during which a source program is translated from a high-level language (such as the C language) into a machine language.

compile
The action required to transform a source file into an object file.

compiler
A program that translates instructions written in a high-level programming language (such as the C language) into a machine language.

complex name
The user-specified name of a loosely coupled complex or stand-alone TPF processor; it forms the second part of the system ID.

computer room agent set (CRAS)
A terminal on which TPF system operators perform supervisory functions and respond to output messages generated internally by the system.

concurrency controls
A way of providing data access controls. TPF collection support (TPFCS) provides three levels of access control: none, optimistic, and pessimistic concurrency.

concurrency filter lock facility (CFLF)
The TPF support for the multi-path lock facility (MPLF).

condition
A relational expression that can be evaluated to a value of either true or false.

conditional compilation statement
A preprocessor statement that causes the preprocessor to omit specified C source code in the file depending on how a specified condition evaluates.

conditional expression
A compound expression that contains a condition (the first expression), an expression to be evaluated if the condition has a nonzero value (the second expression), and an expression to be evaluated if the condition has the value 0.

confirmed status
The term confirmed has two meanings regarding the clocks in loosely coupled processors: local or remote.

If a processor is confirmed local, its clock is internally synchronous but is not synchronous with the complex. If a processor is confirmed remote, the processor clock is continually being verified through the TOD RPQ or a Sysplex Timer (STR). As a condition for operation, a tightly coupled processor complex must be internally synchronous; that is, all the I-stream engines must be synchronous with the main I-stream engine. The master processor is defined to be locally confirmed if the TOD RPQ is used. The master processor is defined to be remotely confirmed if a Sysplex Timer (STR) is used.

CONKC tag
The symbolic name of a system configuration variable.

connect token
A token that identifies a connection to the coupling facility (CF) list structure and is unique for each connection in the processor configuration.

connection
A virtual circuit or session established between two MPIF users for passing data or commands between themselves. A connection has a specific pair of tokens that identify the MPIF resources used for the connection.

connection services
Services that allow authorized programs and subsystems to use the coupling facility (CF) to share data in a processor configuration.

connections
See user.

connector
See user.

constant
A data object with a value that does not change during program execution.

constant expression
An expression having a value that can be determined during compilation and that does not change during program execution.

continuous data collection (CDC)
An application that gathers online system performance data relating to TPF production system environments and stores the data in a relational database by using the TPF Application Requester (TPFAR) feature.

control point logical unit (CLU)
Control LUs (CLUs) are the mechanisms used to establish LU-LU sessions in an SNA PU 2.1 and PU 5 environment. A VTAM application program, called the logon manager, has a session with a TPF CLU to exchange session initiation requests.

control program (CP)
A computer program designed to schedule and to supervise the execution of programs of a computer system.

control program macros
Macros that link an application to the system service routines, or activate internal control program functions. Contrast with application macros.

control record
A pool record that serves as the anchor to which all of the parts that represent an associated collection are chained.

control station
In a BSC network, the station (usually a processor) in a multipoint data communications system that controls network traffic by means of polling and selection. On a centralized multipoint network, tributary stations can communicate only with the control station when polled or selected by the control station.

control statement
A C language statement that changes the path of execution.

control transfer
The facility used to move from the control program environment to the ECB-controlled environment. The interface is the CXFRC macro.

control vector (CV)
A field containing certain information in an SNA path information unit (PIU). Multiple SNA commands can share the same control vector.

conversation
A logical connection between 2 programs over an SNA LU 6.2 session that allows them to communicate with each other while processing a transaction. A conversation provides a short-term connection between 2 particular programs, while a session is a long-term connection between a particular pair of LUs.

conversation control block (CCB)
An area in main storage used to identify and control an LU 6.2 conversation.

conversation state
The condition of a conversation that reflects what the past action on that conversation has been and that determines what the next set of actions may be.

conversion
A change in the type of a value. For example, when you add values having different data types, the compiler converts both values to a common form before adding the values.

copy member
A file that is copied into a control section (CSECT). For example, CICR40 is a copy member of CCNUCL.

core allocation lists
See main storage allocation lists.

core block reference word (CBRW)
An 8-byte field in the entry control block (ECB) that is used to hold the main storage address and dynamic information about main storage blocks in use while the entry is active. Every ECB has 16 CBRWs, one for each ECB data level. Additional CBRWs are available by using data event control blocks (DECBs).

core image records
The system records placed in main storage by IPL during system restart.

core image restart area
An area that contains TPF load modules that must be loaded into contiguous storage. It consists of the CP, FCTB, RIAT, SIGT, ICDF, ACPL, IPAT, USR1, and USR2. The CP is not self-relocating and must therefore be loaded into a fixed storage location. The remaining load modules are self-relocating.

core resident program
An ECB-controlled program that is brought into main storage when it is entered and remains in main storage. Core resident programs reside in an area called the core resident program area (CRPA).

core resident program area (CRPA)
The area of main storage in which core resident programs reside.

coupling facility
A special processor used to centralize storage for all attached processors in a processor configuration by providing shared storage management functions.

coupling facility cache structure
A named piece of storage on the coupling facility (CF) that enables the TPF system to share information. A coupling facility cache structure allows high-performance sharing of frequently referenced data.

coupling facility connection block (CFCB)
A dynamic coupling facility (CF) control block that represents a single connection to a CF structure.

coupling facility control table (CFCT)
A coupling facility (CF) table that contains information such as pointers to other tables and locks for CF resources that are global to CF support.

coupling facility lock
A lock that is used to by coupling facility (CF) support. See lock.

coupling facility list structure
A named piece of storage on the coupling facility (CF) that enables TPF systems to share information. A CF list structure contains a set of lists and an optional lock table that can be used for serializing resources in the list structure. Each list contains a queue of list entries.

coupling facility name
A 5- to 8-character alphanumeric name, that begins with an alphabetic character, that is used by the TPF system to identify the coupling facility (CF).

coupling facility request block (CFRB)
A dynamic coupling facility (CF) area that monitors the progress of a CF macro call.

coupling facility status table (CFST)
A coupling facility (CF) table that contains multiple entries. Each entry contains information particular to a CF in the processor configuration.

coupling facility structure
See coupling facility list structure and coupling facility cache structure.

coupling facility structure block (CFSB)
A dynamic coupling facility (CF) area maintained in both main storage and fixed file records that contains information about a CF structure.

coupling facility trace table (CFTT)
A coupling facility (CF) table that contains CF trace data for use by IBM service representatives.

coupling facility vector block (CFVB)
A dynamic coupling facility (CF) area that is used to handle the completion of CF requests and to monitor list transitions.

CP
Control program.

CPC
Central processor complex.

CPGID
CPGID is another word for the numerical part of the CodesetRegistry-CodesetEncoding name.

CPU
Central processing unit.

CPU affinity
An attribute assigned to a program that is restricted to run on a particular I-stream engine in a tightly coupled processor complex.

CPU ID
The symbolic ID given to a CPU, which is also used to distinguish different processors in a loosely coupled processor complex. The CPU ID forms the third part of the system ID.

CPU loop
The routines that sequentially interrogate system queues and clocks to determine what work the CPU will process next. The CPU loop is also known as the system task dispatcher.

CPU loop list
One of the queues interrogated by the CPU loop routines to determine which work items are to be dispatched. These queues are commonly called CPU lists. The queues interrogated, in the order of processing priority, are: cross list, ready list, input list, and deferred list.

CRAS
Computer room agent set.

CRAS state
One of 5 system states. CRAS state supports clock management and keypoint update. Disk lost interrupt is active.

CRAS table (CRAT)
A list of CRAS terminals and their attributes. The CRAT defines the functions each CRAS terminal can perform and provides its address.

CRAS terminal
Variation of computer room agent set.

CRAT
CRAS table.

CRC
Cyclic redundancy check.

created entry
An entry (ECB) established through the use of a create macro, as opposed to an entry (ECB) associated with a given input message.

create macro
An application macro that allows independent entries (ECBs) to be created.

create-type macro
See create macro.

cross-domain takedown
A deactivation request between domains.

cross list
The highest priority CPU loop list, used for dispatching entries among several I-stream engines.

CRPA
core resident program area.

C task communications area (CTCA)
(1) A global data area that is used by the standard C library. (2) Part of the library function work area in the first stack frame attached to an ECB. The CTCA is used by IBM C/370 compiler-generated code. This area contains a set of pointers to the current C locale, a set of floating point constants used by the string conversion functions, and other data needed by various C library functions.

CTCA
C task communications area.

CTKX
Image pointer record. Synonymous with IPR.

CTL dump
The dump produced when processing stops because the control program or hardware has detected an error. For example, a catastrophic error will initiate a CTL dump.

C-type program
(1) A control program CSECT that always resides in main storage and does not require an ECB. (2) A TPF control program CSECT that always resides in main storage, does not require an ECB, and is not required to conform to standard fixed block sizes.

current directory
The directory a user is working with. Synonymous with current working directory, working directory.

current NCB directory records
The node control block (NCB) directory records that are currently being used by the TPF system.

current working directory
The directory a user is working with. Synonymous with current directory, working directory.

cursor
In TPF collection support (TPFCS), a temporary marker that is used to iterate through collections and establish locks on collections.

CV
Control vector.

cycle-down
The process of bringing the system to a lower system state; this implies a decrease in the number of active system resources and a more limited operating condition.

cycle-up
The process of bringing the system to a higher system state; this implies an increase in the number of active system resources and an expanded operating condition.

cyclic redundancy check (CRC)
A method of error detection used to improve the reliability of communication lines.