If, however, it is necessary to redistribute the key boundaries but not to change the number of clusters, then perform the following additional step. Patch the number of clusters in the MHCR record for the appropriate CDS to X'FF' immediately before shutting DFSMShsm down for the reorganization. A value of X'FF' in the number of clusters field signals to DFSMShsm that the user is intentionally modifying the key boundaries; users can immediately create the appropriate CDS backup to maintain the recoverability of the control data sets. If you have not invalidated the number of clusters but restart DFSMShsm after the reorganization, DFSMShsm issues message ARC0130 RC=13, and then it shuts down. This is done to prevent the CDS from becoming irrecoverable should an error occur.

To change the key boundaries in a multicluster CDS, perform the following steps:

1. Issue a FIXCDS command to set the one byte field in the MHCR that contains the number of clusters for the appropriate CDS to X'FF'.
2. After invalidating the number of CDS cluster in the MHCR record, shut down DFSMShsm and follow the steps in Steps for converting to a multicluster control data set for converting to a multicluster control data set. As you restart DFSMShsm, it dynamically determines the key boundaries that are in your new clusters and it issues message ARC0087I to prompt you to perform the CDS version backup. Perform the CDS version backup immediately after you restart DFSMShsm. Figure 1 shows sample FIXCDS commands that you can use to clear the number of clusters in a multicluster CDS.

    FIXCDS S MHCR PATCH(X'159' X'FF') /* MCDS */
    FIXCDS S MHCR PATCH(X'15A' X'FF') /* BCDS */