Tuning to improve memory use

Memory requirements of the ORDER command option

Jobs that use ORDER NO require that all partitions of a table space be open at one time, and therefore have a higher memory requirement. Jobs that use ORDER YES require that only one partition per task be opened at one time.

Tuning sort processing

Specifying a value greater than 0 for the SORTNUM installation or command option tells REORG PLUS that BMCSORT will dynamically allocate sort work data sets as needed, which should eliminate sort work constraints. The amount of sort multitasking that REORG PLUS performs depends on the number of CPUs, the SMAX or MAXSORTS option value, and available memory. You might be able to improve performance by adjusting the SMAX or MAXSORTS option value.

Using multitasking to improve memory use

Multitasking can improve memory use in your reorganization jobs. For information, see Enabling-multitasking-for-performance-in-REORG-PLUS.

Tuning copy processing

The number of copies that you make during a reorganization can affect the memory that your system uses. Balance your site’s backup copy needs with your system’s memory use requirements to determine the optimal number of copy data sets to allocate.

Memory constraints and data set allocation constraints are particularly critical when you are making copies while reorganizing a large number of partitions. Consider one of the following options in this case:

• Specify COPYLVL FULL to have REORG PLUS allocate a single copy data set for the table space.
• If you are reorganizing a subset of contiguous partitions, create a single copy by specifying COPYSUBSET=YES in the installation options module and COPYLVL FULL on your REORG command.
• If you need copies by partition, specify as few copies per partition as possible or consider specifying fewer partitions per job.