You must supply a user exit as a module that is available in the standard module search order.

You may write an exit in any language that allows it to be loaded once and called many times at the module entry point, and conforms to standard OS Linkage conventions.

On entry to the exit module, Register 1 points to an Exit Parameter list supplied by the assembler. The Exit Parameter list has a pointer to an Exit-Specific Information block that contains specific information for each exit type. High Level Assembler provides you with a macro, called ASMAXITP, which lets you map the Exit Parameter list and the Exit Specific Information block.

You specify the name of the exit module in the EXIT assembler option. You can also pass up to 64 characters of data to the exit, by supplying them as a suboption of the EXIT option. The assembler passes the data to your exit during assembler initialization.