The role of CICS

The CICS® recovery manager and the log manager perform the logging functions necessary to support automatic backout. Automatic backout is provided for most CICS resources, such as databases, files, and auxiliary temporary storage queues, either following a transaction failure or during an emergency restart of CICS.

If the backout of a VSAM file fails, CICS backout failure processing ensures that all locks on the backout-failed records are retained, and the backout-failed parts of the unit of work (UOW) are shunted to await retry. The VSAM file remains open for use. For an explanation of shunted units of work and retained locks, see Shunted units of work.

If the cause of the backout failure is a physically damaged data set, and provided the damage affects only a localized section of the data set, you can choose a time when it is convenient to take the data set offline for recovery. You can then use the forward recovery log with a forward recovery utility, such as CICS VSAM Recovery, to restore the data set and re-enable it for CICS use.

Note: In many cases, a data set failure also causes a processing failure. In this event, forward recovery must be followed by backward recovery.

You don't need to shut CICS down to perform these recovery operations. For data sets accessed by CICS in VSAM record-level sharing (RLS) mode, you can quiesce the data set to allow you to perform the forward recovery offline. On completion of forward recovery, setting the data set to unquiesced causes CICS to perform the backward recovery automatically.

For files accessed in non-RLS mode, you can issue a SET DSNAME RETRY command after the forward recovery, which causes CICS to perform the backward recovery online.

Another way is to shut down CICS with an immediate shutdown and perform the forward recovery, after which a CICS emergency restart performs the backward recovery.