Quiescing RLS data sets
Data sets opened by CICS® in RLS mode can also be accessed by batch programs, provided the batch programs open them in RLS mode for read-only processing.
About this task
Batch programs cannot update recoverable data sets in RLS mode, because SMSVSAM prevents it. Thus, to update a recoverable data set from a batch program, first ensure that the data set is closed to all CICS regions. This allows the batch program to open the data set in non-RLS mode for update. (See Switching from RLS to non-RLS access mode.) To enable batch programs to access data sets opened in RLS mode, CICS supports the VSAM RLS data set quiesce and unquiesce functions.
- You want to switch between RLS and non-RLS VSAM access modes.
- You want to prevent data set access during forward recovery.
CICS supports the VSAM RLS quiesce interface by providing an RLS quiesce exit program that is driven for the quiesce and unquiesce functions. CICS regions initiating quiesce and unquiesce requests propagate these to other CICS regions, through the SMSVSAM control ACB and the CICS RLS quiesce exit program.
Other products such as DFSMSdss and CICS VSAM Recovery for z/OS® also communicate with CICS through their SMSVSAM control ACBs and the RLS quiesce exit.