CICS FAQ's part5

TERMINAL CONTROL IN CICS

Evaluate EIBAID
                 When DFHPF1 perform para1

End Evaluate

Handle aid – Depending upon the key pressed control will be transferred
Exec cics Handleaid
PF1 (para one)
End Exec
CMSG ‘message’, R =ALL, S

Where R-terminal id
            S- Send

The enter and PF keys transmit data from the screen, the PA keys tell CICS that a terminal action has taken place but data is not transmitted.

EXEC CICS SEND FROM(data) ERASE END-EXEC, and EXEC CICS RECEIVE INTO(data) LENGTH(length) RESP(data) END-EXEC.

Zero.

INTERVAL/TASK CONTROL IN CICS

The parameters can be passed in the START COMMAND using the options like from, length, rtransid, rtermid and Queue.
The Automatic Time Ordered Transaction Initiation (ATI) is done by using the START command. Similar to Automatic Data-Driven Transaction Initiation done by using the DCT entries. The START command has various options as TRANSID('name'), INTERVAL(hhmmss, S9(7)comp3), TIME(hhmmss, S9(7)comp3), AFTER, AT, HOURS(nnn,s9(8)comp), MINUTES(nnn,s9(8)comp), SECONDS(nnn,s9(8)comp), TERMID('tttt'), FROM(data-value), LENGTH(s9(4) comp), RTERMID(xxxx), RTRANSID(xxxx), QUEUE(xxxxxxxx) (x-are passed to task), REQID(a 8 byte value to cancel). Frequently the TRANSID, TERMID and a Interval option as time are used.

RETRIEVE is used to retrieve data passed to a transaction by using the START command. It has the options as INTO, LENGTH, RTRANSID, RTERMID and QUEUE, which are used to receive respective data sent by START. The CANCEL command can be used to Cancel a START request by using the REQID option.


The retrieve command is used to get data from a task that begins with a START command.

CICS interval control provides a variety of time related features-common commands are ASKTIME, FORMATTIME, START, RETRIEV and CANCEL

Receive command – It is used to receive information from the CICS terminal

E.g.: EXEC CICS RECEIVE
       INTO (WS-AREA)
      LENGTH (WK-LENGTH)
      END-EXEC

Retrieve command –It is used to retrieve information from a transaction that has been initiated by the start command

E.g.: EXEC CICS RETRIEVE
      INTO (WS-AREA)
      LENGTH (N)
      RTRANSID (RETTRN)
      RTERMID (RETQID)
      QUEUE (RETQID)
      END –EXEC

RTRANSID and RTRANID are the transaction and terminal id of the transaction that invoked this transaction.


A particular transaction is started in the following way

EXEC CICS START
TRANSID (---)
TERMID (---)
TIME (083000)
END-EXEC

In this case the transaction is started at 8.30

This is a special application of the start command. STI is achieved in conjunction with the program list table (PLT). The post initialisation (PI) entry of PLT specifies a list of programs that are to be automatically executed by CICS immediately after CICS start-up. This table entry is usually referred to as PLTPI. In order to achieve STI, an STI program must be registered in the PLTPI entry, as well as the ordinary PPT entry. The requirements are the following

In SIT, specify
PLTPI=XX, where XX is the PLT suffix

In PLT, specify

DFHPLT Type =initial
              Suffix =XX
DFHPLT Type =Entry
              Program = name

Immediately after CICS comes up, the program mentioned in PLT table comes up and this issue the following command
EXEC CICS START
TRANSID (---)
TERMID (---)
TIME (083000)
END-EXEC

And thus the transaction is initiated. This program must as usual be registered in the PPT table.

The SUSPEND command is used to suspend a task. During the execution of this command the task will be suspended, and control will be given to other tasks with higher priority. As soon as all higher priority tasks with higher priority tasks have been executed, control will be returned to the suspended task.

EXEC CICS SUSPEND
END-EXEC

The SUSPEND command is used with no options to suspend the current task, by sending it to the end of the Task queue, controlled by the Dispatcher.
Normally an application gives up control whenever it issues a CICS command. In the mean time before the task is re-initiated the Dispatcher gives control to another task and so on.
This allows many tasks to be operating at once, though only one of them only is really being executed by the system.
For most CICS application programs needs very short CPU time utilization requirement before it executes the CICS command. However for very few of them needs a long stretch of CPU time, which could be suspended when it is taking long CPU time, to give control to dispatcher, which prioritizes and executes other tasks of high priority. 

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