Transaction Initiation in CICS

There are multiple ways of initiating a transaction in CICS. Initiating a transaction is nothing but running that transaction to start any process. Below are the different ways of transaction initiation process.

1. Entering the trans ID on native region.

Example: If CST1 is the transaction ID to display the main customer details screen. Then log in to the CICS region and just enter the trans ID ‘CST1’ on the screen so that the corresponding screen gets displayed.

2. By Using START command

START command is used to start a Task at specified interval of time. It has multiple parameters which can be supplied to control the way it initiates that transaction.

Example: If the requirement is to start any transaction from any program, then code it like below. so that the mentioned Trans ID get starts after the specified time interval. START command has many other options apart from the ones mentioned below.

EXEC CICS START
     TRANID(CST2)
     FROM(WS-DATA)
     AFTER HOURS(1)
     RESP(WS-RESP)
END-EXEC.

3. Using PLT (Program List Table):

PLT is the CICS supplied table which holds the transactions that required to be run at the region start UP & SHut DOWN. So the Transactions that are listed in this table are executed at the time of region START UP. Generally all the mandatory trans IDs that should be UP & running when region is active are listed here.

4. By Using Return TRANSID:

REtrun command has the option to use the trans-ID so that the control is given to the program associated with that tran-ID. Return is generally used in an application program to return the control back to OS or to any transactionID.

Example: Below REtun command is coded in an application program as the last statement so that the control is given to TRN1 and the the program associated with TRN1 will be started using the passed Commarea.

EXEC CICS RETURN
     TRANSID(TRN1)
     COMMAREA(WS-COMMREA)
     LENGTH(WS-COMMAREA-LGTH)
END-EXEC.

5. Using TDQ ATI:

Automatic Task Initiation(ATI) is a CICS provided option for Intra-partition TDQs to start any transaction Automatically.
Transaction gets triggered once the specified number of of items are written to the Queue.

Refer the link to get more details on TDQs & TSQs –> http://www.techtricky.com/tsq-and-tdq-in-cics

6. By Assigning Trans-ID to PF/PA keys:

While defining the transaction to PCT, PF/PA keys can be assigned to that using the option TASKREQ=<pf/pa key>. So that by pressing that key triggers that transaction.