Loading user exit routines

You must assemble or compile each user exit as a separate program. If your user exit operates independently, bind or link-edit it separately into a partitioned data set (library) with the member name to be used in the MODS statement. If your user exit operates in conjunction with other user exits in the same phase (for example, E11, E15, and E17 user exits all use the same DCB), you can request DFSORT to dynamically bind or link-edit them together (see MODS statement). Alternatively, you can bind or link-edit them together into a partitioned data set following these rules:

Specify RENT as a bind or linkage editor parameter.
Include an ALIAS statement for each user exit using the external entry name of the routine (for example, the CSECT name).
Specify the appropriate ALIAS name for each user exit on the MODS statement.

DFSORT includes the names and locations of your user exits in the list of modules to be run during each phase. No user exit is loaded more than once in a program phase, but the same user exit can appear in different phases. For example, you can use the same Read Error user exit in both phases, but not twice in one phase.

The length you specify for a user exit must include storage for the user exit itself as well as any storage used by the user exit outside of the load modules such as I/O buffers or COBOL library subroutines. If you specify a ddname for a user exit in the MODS statement, it must match the DD statement that defines the library containing that user exit. For example:

//MYLIB DD   DSNAME=MYRTN, etc.
         .
         .
         .
   MODS   E15=(MODNAME,500,MYLIB,N)