IBM SC34-7012-01 manual Data set name blocks, Reconnecting to SMSVSAM for RLS access, Files

Files

File control information from the previous run is recovered from information recorded in the CICS catalog only.

File resource definitions for VSAM and BDAM files, data tables, and LSR pools are installed from the global catalog, including any definitions that were added dynamically during the previous run. The information recovered and reinstalled in this way reflects the state of all file resources at the previous shutdown. For example:

vIf you manually set a file closed (which changes its status to UNENABLED) and perform a normal shutdown, it remains UNENABLED after the warm restart.

vSimilarly, if you set a file DISABLED, it remains DISABLED after the warm restart.

Note: An exception to the above rule occurs when there are updates to a file to be backed out during restarts, in which case the file is opened regardless of the OPENTIME option. At a warm start, there cannot be any in-flight units of work to back out, so this backout can only occur when retrying backout-failed units of work against the file.

CICS closes all files at shutdown, and, as a general rule, you should expect your files to be re-installed on restart as either:

vOPEN and ENABLED if the OPENTIME option is STARTUP

vCLOSED and ENABLED if the OPENTIME option is FIRSTREF.

The FCT and the CSDxxxx system initialization parameters are ignored.

File control uses the system log to reconstruct the internal structures, which it uses for recovery.

Data set name blocks

Data set name blocks (DSNBs), one for each data set opened by CICS file control, are recovered during a warm restart.

If you have an application that creates many temporary data sets, with a different name for every data set created, it is important that your application removes these after use. If applications fail to get rid of unwanted name blocks they can, over time, use up a considerable amount of CICS dynamic storage. See the CICS System Programming Reference for information about using the SET DSNAME REMOVE command to remove unwanted data set name blocks.

Reconnecting to SMSVSAM for RLS access

CICS connects to the SMSVSAM server, if present, and exchanges RLS recovery information.

In this exchange, CICS finds out whether SMSVSAM has lost any retained locks while CICS has been shut down. This could happen, for example, if SMSVSAM could not recover from a coupling facility failure that caused the loss of the lock structure. If this has happened, CICS is notified by SMSVSAM to perform lost locks recovery. See “Lost locks recovery” on page 89 for information about this process.

Recreating non-RLS retained locks

For non-RLS files, the CICS enqueue domain rebuilds the retained locks relating to shunted units of work.

54CICS TS for z/OS 4.1: Recovery and Restart Guide