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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:
v Disabling 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.
v Disabling other transactions or programs that depend on the satisfactory
operation of a particular program.
v Keeping a count of errors by facility type (transaction or file).
v Abending 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.
v Disabling 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.
164 CICS TS for z/OS 4.1: Recovery and Restart Guide
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