The SCDS data set contains backup copies of target-zone entries that are modified during APPLY processing. These backup copies are made before the entries are (1) changed by inline JCLIN, a ++MOVE MCS, or a ++RENAME MCS or (2) deleted by an element MCS with the DELETE operand. The backup copies are used during RESTORE processing to return the entries to the way they were before APPLY processing.

Each backup copy of an entry is associated with the SYSMOD that caused the entry to be backed up. Together, the collection of entries associated with a SYSMOD is called the BACKUP entry for that SYSMOD. When you process the SCDS (for example, to list entries), you can specify only BACKUP entries; you cannot process individual entries within a BACKUP entry.

Each target zone within a CSI must have its own SCDS. The correct SCDS to be used during processing is determined either by the SMPSCDS DDDEF entry in each specific target zone or by a DD statement in the JCL. An SCDS can be allocated the same way as any normal partitioned data set. The allocation of space and directory blocks for this data set depends on your plans for installing and maintaining functions. For more information about allocating the SMPSCDS, see SMP/E for z/OS Reference.