Dynamic PSBs

Dynamic PSBs are temporary PSBs generated by FM/IMS when a function is started and deleted when it finishes. FM/IMS generates a PSB that is sensitive to all the segments in the specified DBD. If you don't want your function to be sensitive to all segments in a physical DBD, you can use a logical DBD that only includes the physical segments that you want the function to process. For the Extract and Load functions, the PSB is generated with PCBs for the primary database and all logically related databases.

Advantages in using a dynamic PSB

  • A database administrator is not required to generate PSBs for the FM/IMS functions.
  • FM/IMS generates a PSB that best suits the FM/IMS function.

Disadvantages in using a dynamic PSB

  • The same processing option (PROCOPT) is used for all segments in the DBD. For example, you cannot prevent the Edit from updating one segment type in the DBD.
  • A dynamic PSB can access any database in the subsystem, so unless special measures are taken they can be a security risk. See Controlling access to databases by FM/IMS functions for a description of some special measures that can be taken to remove this security risk.
  • The PSB is not available for use if Batch Backout is required.

IMS system considerations

For information on how to customize IMS to support dynamic PSBs, see Customizing IMS to support the use of dynamic PSBs.