Tuning to improve memory use

Use the information in this topic to help you improve memory usage.

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 or ORDER PRESORTED require that only one partition per task be opened at a time. ORDER PRESORTED also eliminates the need to sort the clustering index.

Tuning memory use in sort processing

Specifying a value greater than 0 for the SORTNUM option (with DDTYPE SORTWORK ACTIVE NO and no sort work data sets specified in the JCL) tells LOADPLUS that BMCSORT will control sort work allocations, which should eliminate sort work constraints.

The amount of multitasking that sort processing performs depends on the number of CPUs, the SMAX or MAXSORTS option value, the number of sort work data sets, the number of SORTOUT data sets, and available memory. You might be able to improve memory usage by adjusting the SMAX or MAXSORTS option value or the number of sort work data sets.

Using multitasking to improve memory use

Multitasking can improve memory use in your load jobs.

For information, see Enabling-multitasking-for-performance-in-LOADPLUS.

Tuning memory use in copy processing

The number of copies that you make during a load job can affect the memory that your system uses.

Balance your organization’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 loading a large number of partitions. Consider one of the following options in this case.

• If you are dynamically allocating copy data sets, specify COPYLVL FULL to have LOADPLUS allocate a single copy data set for the table space.
• If you are loading a subset of contiguous partitions, create a single copy by specifying COPYSUBSET=YES in the installation options module. Also, if you are dynamically allocating copy data sets, specify COPYLVL FULL on your LOAD command.
• If you need copies by partition, specify as few copies per partition as possible or consider specifying fewer partitions per job.