All communication is done using the parameter lists fields. The parameter list is mapped by the macro EDGPL300 as shown in Installation exit mapping macro: EDGPL300.

The same parameter list area is passed to each exit module associated with the exit. Each exit module can update the output area of the parameter list to indicate what processing is required by DFSMSrmm. Depending on the order of the exit routines, your exit module might receive the parameter list before any other exit module has processed it, or it might already have been processed. Before taking a decision in your exit routine, you should check to see if an earlier exit routine has already taken a decision. You should be prepared for your decision to be negated by other exit routine processing.