DBFP= parameter for procedures

Use the DBFP= parameter in procedure to specify a 1- to 4-digit value that determines how often the IMS Fast Path buffer pool manager can page free unneeded buffers. The default value of 0 indicates that any unneeded buffers are page freed at each dependent region termination.

This parameter applies only to the Fast Path buffer pool as defined by the DBBF, DBFX, and BSIZ parameters. It is not valid for the Fast Path 64-bit buffer manager.

Specifying a value for this parameter can improve z/OS® performance when many IMS dependent regions with NBA and OBA specified are started and terminated in a short time period (for example, within a period of 1 second). When many page-fixed buffers exist within the z/OS system, specifying a value for this parameter can decrease the z/OS overhead that is required to page fix and page free buffers.

This parameter alters only the method of managing the page fixing and page freeing of the IMS Fast Path buffers in the IMS Fast Path buffer pool. It does not affect the number of buffers in the buffer pool.

0: Allows the number of page-fixed buffers to fluctuate at each termination.
1: Allows the number of IMS Fast Path page-fixed I/O buffers to increase, without a corresponding free. If this option is selected, the number of page-fixed buffers only increases.
2-3600: Determines how often (in seconds) unneeded buffers can be page freed. During this time interval, the number of page-fixed buffers only increases; no page freeing is performed. When the specified time interval expires, the number of page-fixed buffers is reset to the minimum number of buffers needed to satisfy the current requirements.