User-exit work area and work area extension
When you use one of the user exits, the compiler provides a work area and work area extension in which you can save the address of storage obtained by the exit module. Having such work areas lets the module be reentrant.
The user-exit work area (for use by INEXIT, LIBEXIT, and PRTEXIT) consists of 4 fullwords that reside on a fullword boundary. The user-exit work area extension (for use by MSGEXIT) consists of 8 fullwords also on a fullword boundary. These fullwords are initialized to binary zeros before the first exit routine is invoked, and are passed to the exit module in a parameter list. After initialization, the compiler makes no further reference to the work areas.
Related references
Processing of INEXIT
Processing of LIBEXIT
Processing of PRTEXIT
Processing of MSGEXIT
Processing of INEXIT
Processing of LIBEXIT
Processing of PRTEXIT
Processing of MSGEXIT