Information your routine passes to DFSORT at E18 user exit

When you return to DFSORT, you must place the address of a parameter list in general register 1:

When you return to DFSORT, you must place the address of a parameter list in general register 1:Byte 1
Bytes 2 through 4
05 Address of VSAM user exit list
06 Address of password list
00 000000

If QSAM parameters are passed instead, they are accepted but ignored.

Either address entry can be omitted; if they both are included, they can be in any order.