GRS considerations

Global Resource Serialization (GRS) must be installed to access the RCDSs from more than one MVS system.

CICS® VR issues an ENQ for the QNAME DWWCON and a RNAME of each of the recovery control data sets. This ENQ is issued with a scope of SYSTEMS when accessing the RCDSs. If you are using GRS for resource serialization, you do not need to do anything for GRS because this ENQ is propagated to all systems within a GRSplex. If you are using GRS, do not have an entry for this QNAME in the GRS Exclusion list, Conversion list, or Inclusion list as this can cause serialization problems and possibly damage your RCDSs. If you are using a product other than GRS for resource serialization, you need to ensure that the ENQ's issued by CICS VR are propagated to all systems that are sharing the RCDS to avoid damaging or corrupting your RCDSs.

The sample batch job Figure 1 allocates three recovery control data sets.

Figure 1. AMS Commands to Define the CICS VR RCDS

 //ALLOC    EXEC PGM=IDCAMS
 //SYSPRINT DD SYSOUT=*
 //SYSIN    DD *
   DEFINE CLUSTER                                –
       (NAME('hlq.slq.DWWCON1.GRPsuffix')         –
        VOLUMES(TSOL01)                          –
        CYLINDERS(200 30)                        –
        LINEAR                                   –
        SHR(3 3))

   DEFINE CLUSTER                                –
       (NAME('hlq.slq.DWWCON2.GRPsuffix')        –
        VOLUMES(TSO007)                          –
        CYLINDERS(200 30)                        –
        LINEAR                                   –
        SHR(3 3))

   DEFINE CLUSTER                                –
       (NAME('hlq.slq.DWWCON3.GRPsuffix')        –
        VOLUMES(TSOL02)                          –
        CYLINDERS(150 30)                        –
        LINEAR                                   –
        SHR(3 3))
 /*

In the example in Figure 1:

hlq.slq is the CICS VR RCDS prefix defined in the active IGDSMSxx PARMLIB member.
suffix is the CICS VR XCF group name suffix defined in the active IGDSMSxx PARMLIB member.

To protect against loss of recovery data, each recovery control data set is defined on a separate volume. Also, to detect when the RCDSs are becoming full, the third RCDS is smaller than the other two RCDSs.