Optionally, a maximum of eight user trailer labels (UTL1-UTL8) can immediately follow the data set trailer labels. These labels contain user-specified data that can be made available to your program for processing.

If you want the system to write user trailer labels or to make user trailer labels available to your program, you must specify SUL on the LABEL parameter of the DD statement and specify the address of a user trailer label routine in the DCB exit list. The exit list can address several user trailer label routines, that is, routines that process input user trailer labels and create output user trailer labels. The DCB exit list (EXLST) is described in z/OS DFSMS Using Data Sets.