DFSORT input/user exit/output logic examples

Figure 1 gives examples of the logic flow for sort, copy, and merge applications as it relates to SORTINnn, E15 or E35 user exits, and SORTOUT. The intent is to show how your E15 and E35 user exits fit into the logic of an application. All possible paths are not covered. For simplicity, it is assumed that all of the applicable data sets and exits are present and that records are not inserted or deleted. (For a merge, similar logic would be used if an E32 user exit supplied the records rather than SORTINnn data sets.)

Figure 1 illustrates the following logic:

E15 and E35 user exits continue to be entered until they pass back a return code of 8. If your user exit passes a return code of 8 to DFSORT when input records still remain to be processed, the records are processed by DFSORT without being passed to your exit.
During a sort, each record is read from SORTIN and passed to E15 user exit. When all of the records have been processed in this manner, they are sorted by DFSORT, then each sorted record is passed to E35 and written to the output data sets.
During a copy, each record is read from SORTIN, passed to E15 and E35 user exits, and written to the output data sets.
During a merge, one record is initially read from each SORTINnn data set. The record to be output is chosen, passed to E35, and written to the output data sets. The chosen record is then replaced by reading a record from the same SORTINnn data set and the process continues.
Note: For a merge application, records deleted during an E35 user exit routine are not sequence-checked. If you use an E35 user exit routine without an output data set, sequence checking is not performed at the time the records are passed to the E35 user exit; therefore, you must ensure that input records are in correct sequence.

Table 1. Functions of Routines at Program User Exits (Sort)
Functions of Routines at Program User Exits (Sort)Functions	Sort Input Phase	Sort Output Phase
Open/Initialize	E11, E15 user exits	E31 user exit
Modify control fields	E61 user exit	N/A
Insert, Delete/Alter	E15 user exit	E35 user exit
Sum records		E35 user exit¹
Handle special I/O conditions: QSAM/BSAM and VSAM SORTIN QSAM/BSAM SORTOUT VSAM SORTOUT	E18 user exit E19 user exit² N/A	E38 user exit² E39 user exit³ E39 user exit³
Determine action when intermediate storage is insufficient	E16 user exit⁴	N/A
Close/housekeeping	E15, E17 user exits	E35, E37 user exits
Terminate DFSORT	E15 user exit	E35 user exit
Note: The SUM control statement can be used instead of your own routine to sum records. Applies only to a tape work data set sort. E39 can be used for SORTOUT, but not for OUTFIL data sets. Applies only to a tape work data set sort or a Peerage/Vale sort without work data sets.

Table 2. Functions of Routines at Program User Exits (Copy and Merge)
Functions of Routines at Program User Exits (Copy and Merge)Functions	Copy	Merge
Open/Initialize	E15, E31 user exits	E31 user exit
Modify control fields	N/A	E61 user exit
Insert	E15, E35 user exits	E32, E35 user exits
Delete/alter	E15, E35 user exits	E35 user exit
Sum records	E35 user exit	E35 user exit¹
Handle special I/O conditions: QSAM/BSAM and VSAM SORTIN(nn) QSAM/BSAM and VSAM SORTOUT	E38 user exit E39 user exit	E38 user exit E39 user exit
Close/housekeeping	E35, E37 user exits	E35, E37 user exits
Terminate DFSORT	E15, E35 user exits	E32, E35 user exits
Note: The SUM control statement can be used instead of your own routine to sum records.