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Reconnecting to SMSVSAM for RLS access
As on a warm restart, CICS connects to the SMSVSAM server. In addition
to notifying CICS about lost locks, VSAM also informs CICS of the units of
work belonging to the CICS region for which it holds retained locks. See
“Lost locks recovery” on page 89 for information about the lost locks
recovery process for CICS.
CICS uses the information it receives from SMSVSAM to eliminate orphan
locks.
RLS restart processing and orphan locks
CICS emergency restart performs CICS-RLS restart processing during
which orphan locks are eliminated. An orphan lock is one that is held by
VSAM RLS on behalf of a specific CICS but unknown to the CICS region,
and a VSAM interface enables CICS to detect units of work that are
associated with such locks.
Orphan locks can occur if a CICS region acquires an RLS lock, but then
fails before logging it. Records associated with orphan locks that have not
been logged cannot have been updated, and CICS can safely release them.
Note: Locks that fail to be released during UOW commit processing cause
the UOW to become a commit-failed UOW. CICS automatically retries
commit processing for these UOWs, but if the locks are still not released
before the CICS region terminates, these also are treated as orphan locks
during the next restart.
Recreating non-RLS retained locks
Recovery is the same as for a warm restart. See “Recreating non-RLS
retained locks” on page 54 for details.
Temporary storage
Auxiliary temporary storage queue information for recoverable queues only is
retrieved from the warm keypoint. The TS READ pointers are not recovered and
are set to zero.
If a nonzero TSAGE parameter is specified in the temporary storage table (TST), all
queues that have not been referenced for this interval are deleted.
Transient data
Recovery of transient data is the same as for a warm start, with the following
exceptions:
v Non-recoverable queues are not recovered.
v Physically recoverable queues are recovered, using log records and keypoint
data. Generally, backing out units of work that were in-flight at the time of the
CICS failure does not affect a physically recoverable TD intrapartition data set.
Changes to physically recoverable TD queues are committed immediately, with
the result that backing out a unit of work does not affect the physical data set.
An exception to this is the last read request from a TD queue by a unit of work
that fails in-flight because of a CICS failure. In this case, CICS backs out the last
read, ensuring that the queue item is not deleted by the read. A further
exception occurs when the read is followed by a “delete queue” command. In
this case, the read is not backed out, because the whole queue is deleted.
Chapter 6. CICS emergency restart 63