This parameter is used by the SQL optimizer to help estimate how much buffer pool will be available at run-time for the access plan chosen. Increasing this parameter can influence the optimizer to choose an access plan for queries that will be more conservative in its buffer pool usage.
Recommendation: When running DB2 in a multi-user environment, particularly with complex queries and a large buffer pool, you may want the SQL optimizer to know that multiple query users are using your system so that the optimizer should be more conservative in assumptions of buffer pool availability.
When setting this parameter, you should estimate the number of heavy query applications that typically use the database. This estimate should exclude all light OLTP applications. If you have trouble estimating this number, you can multiply the following:
As with adjusting other configuration parameters that affect the optimizer, you should adjust this parameter in small increments. This allows you to minimize path selection differences.
You should consider rebinding applications (using the REBIND PACKAGE command) after changing this parameter.