Handling special I/O

DFSORT contains four exits to handle special I/O conditions: E18 and E38 user exits for SORTIN and SORTINnn, and E19 and E39 user exits for SORTOUT (but not for OUTFIL data sets). They are particularly useful for a tape work data set sort. With all disk work data set sorts, E19 and E38 user exits are ignored.

You can use these exits to incorporate your own or your site's I/O error recovery routines into DFSORT. Your read and write error routines must reside in a partitioned data set (library). Your library routines are brought into main storage with their associated phases. When DFSORT encounters an uncorrectable I/O error, it passes the same parameters as those passed by QSAM/BSAM or VSAM. If no user routines are supplied and an uncorrectable read or write error is encountered, DFSORT issues an error message and then terminates.

With QSAM/BSAM, the following information is passed to your synchronous error routine:

General registers 0 and 1 are unchanged; they contain the information passed by QSAM/BSAM, as documented in the data management publications.
General register 14 contains the return address of DFSORT.
General register 15 contains the address of your error routine.

VSAM will go directly to any routine specified in the EXLST macro you passed to DFSORT via the E18, E38, or E39 user exit, as appropriate. Your routine must return to VSAM via register 14. For details, see z/OS DFSMS Macro Instructions for Data Sets or z/OS DFSMS Using Data Sets