IBM SC34-7012-01 manual Your own PEP

7.	The CICS transaction failure program, DFHTFP, links to DFHPEP before
	transaction backout is performed. This means resources used by the abending
	transaction may not have been released. DFHPEP needs to be aware of this,
	and might need logic to handle resources that are still locked.
8.	Do not use the restart function for distributed transactions whose principal
	facilities are APPC links. In some error situations, CICS cannot resolve the
	APPC conversation states, and your transaction will abend with code AZCP.

Your own PEP

During the early phases of operation with CICS, the master terminal commands can put abending transactions into disabled status while the cause of the abend is being investigated and corrected.

Where a program needs to handle this process, or where associated programs or transactions should also be disabled, you might decide to incorporate these actions in your own PEP. This will depend on the importance of the applications being served.

The program error program is a command-level program that can be written in any of the languages that CICS supports. The CICS abnormal condition program passes to the PEP a communications area (COMMAREA) containing information about the abend. You can add code to take appropriate actions to suit your requirements.

Functions you might consider including in a program error program include:

vDisabling a particular transaction identifier (to prevent other users using it) pending diagnostic and corrective actions. This avoids the need to use CEMT commands and the risk of several more abends in quick succession.

vDisabling other transactions or programs that depend on the satisfactory operation of a particular program.

vKeeping a count of errors by facility type (transaction or file).

vAbending CICS after a transaction abend. Conditions for this might be:

–If the abended transaction was working with a critical file

–If the abended transaction was critical to system operation

–If the abend was such that continued use of the application would be pointless, or could endanger data integrity

–If the error count for a particular facility type (transaction or file) reached a predetermined level.

vDisabling the facility, which would keep the system running longer than if you cause CICS to abend.

If a task terminates abnormally (perhaps because of a program check or an ABEND command), code in a program-level exit or the PEP can flag the appropriate transaction code entry in the installed transaction definition as disabled. CICS will reject any further attempt by terminals or programs to use that transaction code until it is enabled again. Consequently, the effect of program checks can be minimized, so that every use of the offending transaction code does not result in a program check. Only the first program check is processed. If the PEP indicates that the installed transaction definition is to be disabled, CICS will not accept subsequent uses of that transaction code.

164CICS TS for z/OS 4.1: Recovery and Restart Guide