IBM SC34-7012-01 manual Intrapartition transient data, Auxiliary temporary storage, START requests

Intrapartition transient data

Intrapartition destinations specified as logically recoverable are restored by transaction backout. Read and write pointers are restored to what they were before the transaction failure occurred.

Physically recoverable queues are recovered on warm and emergency restarts.

Transient data does not provide any support for the concept of transaction backout, which means that:

vAny records retrieved by the abending unit of work are not available to be read by another task, and are therefore lost.

vAny records written by the abending unit of work are not backed out. This means that these records are available to be read by other tasks, although they might be invalid.

CICS does not support recovery of extrapartition queues.

Auxiliary temporary storage

CICS transaction backout backs out updates to auxiliary temporary storage queues if they are defined as recoverable in a temporary storage table. Read and write pointers are restored to what they were before the transaction failure occurred.

CICS does not back out changes to temporary storage queues held in main storage or in a TS server temporary storage pool.

START requests

Recovery of EXEC CICS START requests during transaction backout depends on some of the options specified on the request. The options that affect recoverability are:

PROTECT

This option effectively causes the start request to be treated like any other recoverable resource, and the request is committed only when the task issuing the START takes a syncpoint. It ensures that the new task cannot be attached for execution until the START request is committed.

FROM, QUEUE, RTERMID, RTRANSID

These options pass data to the started task using temporary storage.

When designing your applications, consider the recoverability of data that is being passed to a started transaction.

Recovery of START requests during transaction backout is described below for different combinations of these options.

START with no data (no PROTECT)

Transaction backout does not affect the START request. The new task will start at its specified time (and could already be executing when the task issuing the START command is backed out). Abending the task that issued the START does not abend the started task.

START with no data (PROTECT)

Transaction backout of the task issuing the START command causes the START request also to be backed out (canceled). If the abended transaction is restarted, it can safely reissue the START command without risk of duplication.

START with recoverable data (no PROTECT)

Transaction backout of the task issuing the START also backs out the data

76CICS TS for z/OS 4.1: Recovery and Restart Guide