Allocating space for the control data set

When you allocate the DFSMSrmm control data set index and data components, the index and data components must be on the same volume because DFSMSrmm does not support them being allocated on separate volumes.

Use JCL similar to that shown in Figure 1 to allocate space for the control data set on the master system:

Figure 1. Allocating DASD space for the control data set

//IDCAMS   EXEC PGM=IDCAMS,REGION=1M
//SYSPRINT DD   SYSOUT=*
//DASD     DD   DISP=SHR,UNIT=SYSDA,VOL=SER=8E5U04
//SYSIN    DD   *
 DEFINE CLUSTER(NAME(RMM.CONTROL.DSET) -
                FILE(DASD) -
                FREESPACE(15 0) -
                KEYS(56 0) -
                REUSE -
                RECSZ(512 9216) -
                SHR(3 3) -
                KILOBYTES(4500 1500) -
                STORAGECLASS(gspace) -
                VOLUMES(8E5U04)) -
           DATA(NAME(RMM.CONTROL.DSET.DATA) -
                BUFFERSPACE(829440) -
                CISZ(26624)) -
          INDEX(NAME(RMM.CONTROL.DSET.INDEX) -
                CISZ(2048))
  /*

Recommendation: Use a CISZ of 26624 bytes and BUFFERSPACE of 829440 bytes for the data component of the control data set to help improve inventory management run times through reduced I/O to the control data set. Any suitable CISZ between 10240 and 26624 that meets your needs can be used.

where:

KILOBYTES: Is the space value you calculated in Calculating DASD space for the DFSMSrmm control data set. Choose a secondary space value that allows the control data set to grow in the future.
NAME(): Specifies the name of the control data set. Use the same name you assigned in the parmlib member EDGRMMxx under OPTION DSNAME(name) or in the MASTER DD statement in the DFSMSrmm procedure.
FREESPACE: Specifies how much free space VSAM reserves in the data set for future additions. Free space is specified for control intervals (CI) to allow for the variable length records used by DFSMSrmm. Specifying a zero value for control area (CA) freespace ensures that CA splits create free space where it is required. For more information on changing the FREESPACE values, see z/OS DFSMS Using Data Sets.
BUFFERSPACE: When the buffer space value is large enough to accommodate a data CA plus one data CI and one index CI, you benefit from improved performance during IDCAMS REPRO.