Before returning control to DFSORT, your routine passes the DCB fields in a parameter list by placing the parameter list address in general register 1. The list must begin on a fullword boundary and must be a whole number of fullwords long. The first byte of each word must contain a character code that identifies the parameter. Either word can be omitted. A word of all zeros indicates the end of the list.

If VSAM parameters are passed, they are accepted but ignored.

The format of the list is as follows:

SYNAD

This field contains the location of your write synchronous error routine. This routine is entered only after the operating system has unsuccessfully tried to correct the error. It must be assembled as part of your own routine.

EXLST

The EXLST field contains the location of a list of pointers. These pointers point to routines that are used to process labels and accomplish other tasks not handled by data management. This list, and the routines to which it points, must be included as part of your own routine.

A full description of these DCB fields can be found in z/OS DFSMS Macro Instructions for Data Sets.