Before you can use the SnapShot function for virtual concurrent copy, you must ensure that working space is available by allocating working space data sets (WSDS) on one or more volumes in the same RAMAC Virtual Array (RVA) subsystem as the source data sets. System Data Mover (SDM) uses the working space data sets as the intermediate location for virtual concurrent copy.

The naming convention for these working space data sets is:

SYS1.ANTMAIN.Ssysname.SNAPnnnn.

Variable sysname is the system identifier and nnnn is a four-digit decimal number in the value range 0001-9999. If the system identifier is eight characters, 'S' replaces the first character.

The SnapShot working space data sets must be physical sequential, non-extended-format, single volume, and cataloged. SDM performs a numerically sequential catalog search for each data set, starting with hlq.ANTMAIN.Ssysname.SNAP0001 until a data set is found or until it encounters a catalog locate error, indicating that the data set was not found. SDM does not use working space data sets with the naming convention beyond the data set that was not found. The SnapShot working space data sets can be SMS-managed or non-SMS-managed. You cannot allocate VSAM or multivolume data sets as SnapShot working space data sets.

If you want to allocate secondary space, you must extend the data set by filling it with data before you start the DFSMSdss job. System Data Mover (SDM) does not extend a working space data set. SDM holds an enqueue for the data set when the SnapShot operation uses working space data set and releases the enqueue after SnapShot operation finishes using the data set. You can reallocate or extend a working space data set only when SDM does not have the data set enqueued. SDM uses the new reallocated or extended data set on subsequent runs of the SnapShot operation.

You can add more working space data sets after ANTMAIN completes the initialization process. SDM uses these data sets the first time it encounters an out-of-working-space condition during a SnapShot operation. When this condition occurs, SDM refreshes the list of working space data sets by performing a catalog search that starts with SYS1.ANTMAIN.Ssysname.SNAP0001.

The LRECL and block size can be any valid combination. The tracks within the data set are used as the target of SnapShot operations, and you should not try to access them using normal data access methods.