Loading the External Subsystem Attachment Package

During control region initialization, IMS loads external subsystem-supplied tables using the table names specified by the installation (in the external subsystem definition member in IMS.PROCLIB).

IMS loads the external subsystem module table (ESMT) and then loads the external subsystem modules defined in the table. The resource translation table (RTT) is also loaded, if provided. If an error occurs during this process, IMS puts the subsystem in 'stopped' status and does not establish a connection. However, IMS will reaccess the definition (PROCLIB) and reattempt this process if a /START SUBSYS command is received.

Possible errors are:
  • Unable to process the PROCLIB member
  • Unable to open the external subsystem load library
  • Unable to load the ESMT (incorrect name specified, not in library)

IMS stores the addresses of the ESMT and the RTT in the EEVTP control block fields EEVPESMT and EEVPRTTA, respectively.