Placing Db2 for z/OS modules and tables in the appropriate library

IMS loads the modules and tables specified in the external subsystem module table from the Db2 for z/OS libraries when the SSM EXEC parameter is specified in an IMS region. To ensure that this process is successful, you must make the Db2 for z/OS libraries, which must be APF-authorized, available to IMS.

For this purpose, you can either add the Db2 for z/OS libraries to the JOBLIB/STEPLIB/LINKLIST concatenation or create a DFSESL DD statement for this purpose. IMS does not automatically generate a DFSESL DD statement.

If the JOBLIB/STEPLIB/LINKLIST concatenation is not authorized, you must use the DFSESL DD statement. For online IMS regions, the subsystem library or libraries must be concatenated after the library containing the IMS modules (typically IMS.SDFSRESL). When multiple subsystems are connected, additional subsystem data sets can be concatenated.

Note: The DFSESL DD statement is used by IMS to load specific modules or tables and is not part of a general library search.

Example:

 //DFSESL DD  DISP=SHR,DSN=IMS.SDFSRESL
 //       DD  DISP=SHR,DSN=DSNxxx.DSNLOAD
 //       DD  DISP=SHR,DSN=DSNyyy.DSNLOAD

IMS.SDFSRESL is first, followed by the subsystem libraries.

For IMS batch regions, the DFSESL DD statement is not used. The Db2 for z/OS libraries must be in both the JOBLIB/STEPLIB/LINKLIST concatenation and the DFSRESLB DD statement for authorized modules.

If you use the COBOL II dynamic option, the Db2 for z/OS libraries must be added to the JOBLIB or STEPLIB regardless of authorization. The DD statement that specifies IMS.SDFSRESL must precede the reference to DSNxxx.DSNLOAD in the JOBLIB or STEPLIB. If the JOBLIB or STEPLIB is not authorized, you must also use a DFSESL DD statement.