IBM SC34-7012-01 Switching from RLS to non-RLS access mode, Exception for read-only operations

Lost locks recovery complete

A quiesce interface function initiated by VSAM. VSAM takes action associated with a sphere having completed lost locks recovery on all CICS regions that were sharing the data set.

SMSVSAM invokes the CICS RLS quiesce exit program in each region that is registered with an SMSVSAM control ACB.

Until lost locks recovery is complete, CICS disallows any new requests to the data set (that is, only requests issued as part of the recovery processing are possible). When lost locks recovery is complete, CICS allows all requests to the data set.

Quiesce coupling facility cache available

A quiesce interface function initiated by VSAM. VSAM takes action associated with an MVS coupling facility cache structure being restored.

SMSVSAM invokes the CICS RLS quiesce exit program in each region that is registered with an SMSVSAM control ACB.

CICS retries any backout-failed shunted units of work for all data sets.

Switching from RLS to non-RLS access mode

The main reason why you might need to switch a data set from RLS access mode to non-RLS access mode is to run a batch update program that cannot be changed to run as a CICS transaction.

About this task

Non-RLS access mode is a generic term embracing NSR, LSR, and GSR access modes. It is likely that your existing batch programs open VSAM data sets in NSR access mode, although it is also possible for batch programs to use LSR or GSR.

As a general rule, you are recommended not to switch between RLS and non-RLS within CICS. After a data set is accessed in RLS mode by CICS, it should always be accessed in RLS mode by CICS. The following topic describes an exception to this general rule for read-only operations.

Exception for read-only operations

There is an exception to the general rule about not switching between RLS and non-RLS within CICS.

You can switch to non-RLS access on a data set that is normally opened in RLS mode provided access is restricted to read-only operations. You might want to do this, for example, to allow continued access for read-only transactions while the data set is being updated by a batch job. CICS and VSAM permit quiesced data sets to be opened in non-RLS mode, but you must ensure that CICS transactions do not update a data set that is being updated concurrently by a batch program.

The recommended procedure for providing CICS read access to a recoverable data set while it is being updated by a batch job is:

vResolve retained locks.

vQuiesce the data sets.

vRedefine the files as non-RLS and read-only mode in all relevant CICS regions. You can do this using the CEMT, or EXEC CICS, SET FILE command.

172CICS TS for z/OS 4.1: Recovery and Restart Guide