How to request the use of SB

IMS provides two methods for specifying which of your programs and databases use OSAM sequential buffering (SB).

You can explicitly specify which programs and utilities should use SB during PSB generation or by using SB control statements.
You can specify that by default all or a subset of your batch and BMP programs and utilities should use SB by coding an SB exit routine or by using a sample SB exit routine provided with IMS.

Determine which method you will use. Using the second method is easier because you do not need to know which BMP and batch programs use sequential processing. However, using SB by default can lead to an uncontrolled increase in real and virtual storage use, which can impact system performance. Generally, if you are running IMS in a storage-constrained z/OS® environment, use the first method. If you are running IMS in a non-storage-constrained z/OS environment, use the second method.