CICS Interview questions

Q. What is EIBCALEN ?

A. EIBCALEN is Execution Interface Block Communication Area Length. EIBCALEN indicates the length of the DFHCOMMAREA. EIBCALEN is checked to see if any data has been passed to the application program. EIBCALEN = 0 means that the application program is running for the first time and no data has been passed to it.

Q. What is the difference between TDQ and TSQ?
A. TSQ and TDQ are temporary storages used to transfer data from one program to another.

TSQ – Temporary storage queue.
TDQ – Transient data queue.

TDQ is read destructive. Data will be erased from the queue once it is read.
TDQ can only be read sequentially. TDQs must be defined in DCT table. TDQs can trigger another task automatically.

TSQ is not read destructive. It can be read multiple times. TSQ can be accessed both sequentially and randomly. TSQ does not have trigger functionality. TSQ can be
dynamically defined.

Q. What is the maximum length of DFHCOMMAREA?
A. 32KB.

Q. What is the difference between LINK and XCTL in CICS?
A. Link invokes an application program which is at next lower level.
XCTL invokes an application program which is at the same level.
Link returns back the control to the calling program. XCTL does not return the control to the calling program.

Q. What is the differences between and EXEC CICS XCTL and an EXEC CICS START command?
A. The XCTL command transfer control to another application with the same Transaction ID. The XCTL continues task on the same terminal. START command initiates a new transaction ID. START can initiate a task on another terminal with a new task id.

Q. Explain CICS control tables
A. CICS Control Tables:

System Initialization Table (SNT)
Terminal Control Table (TCT)
Program Control Table (PCT)
Processing Program Table (PPT)
File Control Table (FCT)
Destination Control Table (DCT)
Resource Control Table

– All the transactions must be defined in PCT.
– All the CICS programs must be defined in PPT.
– All the files used in CICS must be defined in FCT.
– All the TDQs must be defined in DCT.
– DB2 programs’ plans must be defined in RCT.

Q. What are different ways to start a CICS transaction?
A.
1. By keying the TRAN-ID on the terminal.
2. By coding an EXEC CICS START in the application program
3.By coding the trans id and a trigger level on the DCT table
4. By coding the trans id in the EXEC CICS RETURN command

Q. Explain the ways data can be passed between CICS programs.
A. Data can be passed between CICS programs using COMMAREA and queues

Two different type of queues:
TRASIENT DATA QUEUE (TDQ) & TEMPORARY STORAGE QUEUE (TSQ).

Data can be passed to a called program using the COMMAREA option of the LINK or XCTL command in a calling program. The calling program receives the data back when the called program issues a RETURN command. The called program does not have to specify the COMMAREA option in the RETURN command.

If the COMMAREA is used in the calling program, the area must be defined in the Working Storage Section of the program, whereas, in the called program, the area must be defined as the first area in the Linkage Section, using reserved name DFHCOMMAREA.

Q. How can we place the cursor at particular field on a map.
A. Move -1 to the field length of the field (Field name +L) in the symbolic map.

Q. What are the CICS commands associated with TDQ and TSQ processing
A. WRITEQ TS, READQ TS, and DELETEQ are used TSQs.
WRITEQ TD, READQ TD, DELETEQ TD, ENQ and DEQ.

Q. Explain ENQ and DEQ commands.
A. When ENQ command is issued on a particular resource the task will be queued to use that resource. ENQ command reserves the resource if the resource is available. DEQ command unlocks the resource.

Q. Explain how EIBAID field is used
A. EIBAID is a key field in the execute interface block. We can check EIBAID field to know which key the user has pressed to initiate the transaction.

Q. Explain CICS system command CEDF
CEDF is CICS-supplied Execution Diagnostic Facility transaction. It provides interactive program execution and debugging functions of a CICS programs.

Q. Explain CICS system command CEMT
CEMT : CICS-supplied Extended Master Terminal transaction. It displays or manipulates the status of CICS resources.
Q. Explain CICS system command CEBR
CEBR is CICS-supplied Temporary Storage Browse transaction. It is used to read the Temporary Storage Queue ( TSQ ).

Q. Explain CICS system command CECI
CECI is CICS-supplied Command Interpreter transaction. It verifies the syntax of a CICS command and executes the command.