CICS

Region

Address space assigned to handle all CICS programs. Can have multiple regions (ex. production, test, etc.)

Multithreading

All users in a CICS region can use the same copy of a program at the same time, however each user will have a separate copy of working storage for their use.

Conversational Program

An online program that sits idle while it waits for user input. While it waits for user input, the task associated with that program remains in storage - inefficient use of virtual storage!

Pseudo-Conversational Program

A program that ends after it sends data to a terminal, which releases some of the resources that are used by the program. CICS restarts the program when the user completes an entry and presses one of the AID keys.

Re-entrant program

A truly reentrant program cannot modify data in working storage, so CICS provides a separate copy of working storage for each user running a program. Ensures multithreading will work. In CICS a program is considered re-entrant if more than one task can execute it without interfering with the execution of other tasks.

What CICS command do you need to obtain the user logon-id?

ASSIGN command of CICS is used to obtain user login-id with the option OPEN ID. Syntax: EXEC CICS ASSIGN OPENID(PRASHANT) END-EXEC

AID keys

Attention Identifier Keys Four of them: Enter key, a PF key, a PA key, and the Clear key.

Multitasking

CICS allows more than one task to be executed at the same time.

CECI

CICS-supplied Command Interpreter transaction It verifies the syntax of a CICS command and executes the command

CEDF

CICS-supplied Execution Diagnostic Facility transaction It provides interactive program execution and debugging functions of a CICS programs.

CEMT

CICS-supplied Extended Master Terminal Transaction A system transaction id for inquiring the status or changing the status of resources. It displays or manipulates CICS control environment interactively.

CEBR

CICS-supplied Temporary Storage Browse transaction It displays the content of Temporary Storage Queue (TSQ).

CWA

Common Work Area An area of storage that's available to all tasks in a CICS system used to store limited amounts of info that might be useful to many or all programs in an installation. Ex. the company name for report headings, the current date in various formats, etc. It varies from installation to installation.

COMMAREA

Communication Area A temporary storage area which is used to pass data between different programs loaded by a transaction and between different transactions at a given terminal.

CICS

Customer Information Control System Allows data to be transmitted from the terminal to the host, processes that data, accesses files and databases, then transmits data back to the terminal.

Common CICS service programs

Data communication services - Allows users to communicate with programs through their terminals. (uses TCT) Data management services - Lets programs access data stored in files or databases. (uses FCT) CICS management services - Provides a variety of services for managing the execution of application programs. *** These services are available to an application program through its API (Application Programming Interface) to insure all services are invoked in a consistent manner.

DCT

Destination Control Table

EIB

Execute Interface Block Each task has one EIB and it exists for the duration of the task. It is the same for all the programs that are part of the task, and are defined in the linkage area of the program.

FCT

File Control Table Contains a list of files used by CICS, record length and their status (closed/open, enabled/disabled), name, type, whether they can be read sequentially or randomly, deleted/modified, and if new records can be added

MDT

Modified Data Tag * The last bit of each field signifies if it has been changed (1) or not (0). * It helps in improving data traffic over communication line because only data with a 1 is sent from the terminal end to the host computer.

PCT

Program Control Table Contains a list of transaction identifiers paired with corresponding program.

PPT

Program Processing Table Contains a list of program names and the BMS mapsets and whether a current version of program is in storage or fresh copy needs to be loaded

RCT

Resource Control Table Contains DB2 plan name and transaction identifier

SOS

Short On Storage When CICS goes short on virtual storage, it suspends all work and begins terminating tasks in an effort to free up storage.

TDQ

Temporary Data Queue TDQ's can be read only once. Records in TDQ can be read only sequentially. A record in a TDQ cannot be updated. TDQs name must first be defined in the DCT (Destination Control Table). TDQ may be used by batch application. TDQ can started automatically a CICS transaction.

TSQ

Temporary Storage Queue Records in TSQ can be read more than once. Records in TSQ can be read randomly. You may update an existing item in a TSQ. TSQ names are dynamically defined in the application program. TSQ cannot be accessed in batch. TSQ cannot started automatically a CICS transaction.

TCT

Terminal Control Table Contains a list of the terminals known to CICS. Makes it possible for CICS to direct program output to the correct terminal and any input from the terminal to the correct program.

Name 3 ways an MDT can be set on

The Modified Data Tag can be set on: 1) When the user enters data into the field 2) When the application program moves DFHBMFSE to the attribute character 3) By defining it in the BMS macro definition

Task

The execution of an application program for a specific user.

Transid

Transaction Identifier A four character code which is used to invoke a CICS task.