Your routines at this user exit can pass DFSORT a parameter list containing the specifications for three data control block (DCB) fields: SYNAD, EXLST, and EROPT. Your E18 user exit routine can also pass a fourth DCB field (EODAD) to DFSORT.

Your routines are entered at the beginning of each phase so that DFSORT can obtain the parameter lists. The routines are entered again during processing of the phase at the points indicated in the parameter lists. For example, if you choose the EXLST option, DFSORT enters your E18 user exit routine early in the sort (input) phase. DFSORT picks up the parameter list including the EXLST address. Later in the phase, DFSORT enters your routine again at the EXLST address when the data set is opened.