IMS External Subsystem Attach Facility processing

The IMS External Subsystem Attach Facility performs processing during control region initialization.

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).
Initiating the external subsystem connection
IMS automatically connects to the external subsystem during control region initialization processing (for example, when IMS is started) unless the external subsystem chooses to defer the control region identify to a later time.
Application program request support
Application calls are passed to IMS from the language interface module that you bind with the application program. The language interface branches to the appropriate IMS program request handler passing the application program call parameter list.
Resource recovery token
A 16-byte recovery token is used to uniquely identify a unit of work across all subsystems to which the application has thread connections. IMS passes the token to the Signon exit routine before the thread is created.
Terminating the external subsystem connection
IMS terminates the external subsystem connection (control region connection) in an orderly manner in a number of different circumstances.

Parent topic: External subsystem attach facilities