In most cases, you can let DFSMSdss determine the amount of storage it uses for an operation. Sometimes, however, you might want closer control of the amount of storage DFSMSdss uses. Use the storage estimates in this topic as a starting point for determining minimum region sizes in which DFSMSdss can run. Table 1and Table 2 show the minimum storage requirements, in bytes, to run each DFSMSdss operation. Table 3 shows the minimum storage requirements, in bytes, to restore partitioned and VSAM data sets to unlike devices. The legend for Table 1, Table 2, and Table 3 is displayed beneath Table 3. The values include the storage required to load the DFSMSdss program into the region.

Storage requirements depend on your operating system configuration and your device and data set characteristics. The storage requirement estimates shown for the COPY, DUMP, and RESTORE commands are only for the full-volume copy, dump, and restore operations; they might vary for a data set operation.

If DFSMSdss determines that the storage requirements are greater than the storage available during processing, DFSMSdss issues error message ADR376E to indicate this. The out-of-storage condition might cause abend 80A during DFSMSdss postprocessing.

If you use buffers above 16 megabytes virtual storage, the buffer size is allocated independently of the region size.

If you use the PARALLEL command to run two or more DFSMSdss tasks concurrently, the total storage required is the sum of the storage required for all functions to be run in parallel. However, because DFSMSdss is reentrant, the DFSMSdss code is not duplicated in storage. Therefore, do not include the DFSMSdss load module size more than once.