Understanding the recovery control data set

The CICS® VR recovery control data set (RCDS) contains essential information for recovering your VSAM spheres.

The RCDS contains information on the following:
  • CICS VR ISPF dialog interface default values
  • MVS log streams
  • MVS log stream copies
  • Registered logical backups
  • Change accumulation data sets
  • CICS VR VSAM batch logging
  • Shadows

This information is stored in three identical linear VSAM data sets. Three data sets are used to reduce the possibility of data loss. CICS VR regularly checks to make sure the three data sets are consistent.

The information in the RCDS is updated under the following conditions:
  • Through the CICS VR ISPF dialog
  • By using the log of logs scan, with CICS TS
  • By using log stream copy, with CICS TS
  • Automatically by CICS VR, with change accumulation
  • Automatically by CICS VR, with VSAM batch logging
  • Automatically by doing a shadow forward recovery
  • Automatically when the CICS VR server address space is active
  • Automatically when CICS VR is notified of a logical backup created for a VSAM data set
  • Automatically when CICS VR is notified of a VSAM backout failure, and recovery or reorganization is requested.
You can reduce the likelihood of your RCDS becoming full by deregistering old information from the RCDS. You can set up automatic deregistration for your log streams (log stream copies or the log-tail), registered backups, and change accumulation data sets using the CICS VR panel interface. In addition, you can instantly deregister the following using the CICS VR dialog interface:
  • Log streams
  • SAM copies of a log
  • Log of logs
  • Registered logical backups

Deregistration is triggered by running scan or automatically by the CICS VR server address space. Once deregistered, CICS VR automatically reuses the freed space in the RCDS; you never need to manually recover free space. For more information on automatic deregistration, see Understanding CICS VR automatic deregistration.

The RCDS must be allocated to a recover job for batch REDO after images unless the recover being run also specifies the REMOTE keyword.

Note: CICS VR issues an ENQ for each of the RCDSs with QNAME DWWCON,RNAME datasetname, and with scope SYSTEMS.