Backup control data set size

The BCDS must be large enough to contain the maximum number of records for all the data sets and volumes that have been backed up.

Figure 1 is an example, based on 3390 DASD, of the BCDS size work sheet (also found in DFSMShsm work sheets). An example calculation follows the work sheet.

To calculate the size of your backup control data set, you need to know the number of backup versions you want to keep and the number of data sets that you want to have automatically backed up.

Note: VSAM extended addressability capabilities allow each BCDS cluster to exceed the 4 GB size. In addition, the BCDS can span up to four unique KSDS clusters. For more information about using VSAM extended addressability capabilities, see Using VSAM extended addressability capabilities. For more information about using KSDS clusters, see Using multicluster control data sets.