To check that your exit is functioning correctly, especially during the early stages of testing, you can enter messages giving the current status of processing. For example, if you are testing a DADSM exit, you can enter a message early in the exit giving the reason for entry (allocate, extend, scratch, partial release, or rename). If you use WTO with a routecode of 11 (sometimes called 'write to programmer'), the message appears on the output of the job that issued the DADSM request. Messages can also indicate that certain data areas have been found successfully and can display selected contents of data areas.

When the exit begins handling large numbers of jobs, remove the code that produces these messages. Large numbers of messages consume system message buffers, and the text unnecessarily adds to the user's output. Some exception messages might be required.