Execs can be stored in either sequential data sets or partitioned data sets (PDSs). A sequential data set contains only one exec, while a PDS can contain one or more execs. In a PDS, each exec is a member and has a unique member name. When a PDS consists entirely of execs, it is called an exec library.

Exec libraries make execs easy to maintain and execute. Your installation can keep commonly used execs in a system library and you can keep your own execs in a private exec library. To learn important information about data sets at your installation, use the Preliminary Checklist.