There are two ways to customize with exits in DFSMS. Choose an installation exit if the areas you need to customize affect every user of a function. These exits affect the entire installation's processing. Or, choose a user exit if the application programmers should have the opportunity to bypass the modification or to use their own. Whichever exit you choose, consider the impact your modifications have on users especially because some changes can only be made with installation exits.

DFSMS is a licensed program and can be modified for your own use only. IBM supports and maintains only unmodified IBM-supplied modules.