APPLFE= parameter for procedures

Use the optional APPLFE= parameter in procedures to specify a 1 to 8-character name of an application front-end routine that is called whenever a message processing program (MPP) is scheduled in a message processing region (MPR).

You can set the APPLFE= parameter using the DFSOPT DD statement in IMS-supplied procedures. The syntax for the APPLFE= parameter is:

APPLFE=char str (No default)

For more information, see DFSOPT DD in DD statements for IMS procedures.

If APPLFE= is specified, the IMS MPP controller performs the following functions:
  • Loads the application front-end routine.
  • Calls the application front-end routine for initialization processing.
  • Calls the application front-end routine when an MPP is scheduled in an MPR.
  • Calls the application front-end routine for shutdown processing when the MPP terminates.
The following describes the interface between the IMS MPP controller and the application front-end routine:
  1. The IMS MPP controller calls the application front-end routine for initialization processing with the input registers set as follows:
    • R0=0
    • R1=0
    • R13=address of caller's save area
    • R14=return address of caller
    • R15=entry point address of the application front-end routine

    The application front-end routine must restore all registers, except register 15, upon return to IMS. Register 15 contains the return code.

  2. The IMS MPP controller calls the application front-end routine when an MPP is scheduled in an MPR with the input registers set as follows:
    • R0=entry point address of the application MPP
    • R1=PCB list to be passed to the application MPP
    • R13=address of caller's save area
    • R14=return address of caller
    • R15=entry point address of the application front-end routine

    The application front-end routine must restore all registers, except register 15, upon return to IMS. Register 15 contains the return code.

  3. The IMS MPP controller calls the application front-end routine to perform shutdown processing when the MPP is terminating:
    • R0=non-zero
    • R1=0
    • R13=address of caller's save area
    • R14=return address of caller
    • R15=entry point address of the application front-end routine

    The application front-end routine must restore all registers, except register 15, upon return to IMS. Register 15 contains the return code.

Note: Because the IMS MPP controller establishes an ESTAE, a program interrupt is intercepted and treated as an application failure when it occurs after the application front-end routine is called and before it returns to the IMS MPP controller. As a result, the IMS MPP controller reinitializes itself, and once again loads and calls the application front-end routine for initialization processing. IMS stops the transaction that is responsible for the interrupt.