EFS01 user exit routine

Processing of user-defined data types with the EFS01 exit routine requires using the function that alters control statements. EFS program requirements at Major Calls 1 and 2 are:

At Major Call 1, the EFS program must provide the control statement request list with the SORT or MERGE operation definer. See Control statement request list or further details.
At Major Call 2, the EFS program must return a new format, D1, on the SORT or MERGE control statement that informs DFSORT to call the EFS01 routine, (the control fields defined with the D1 format are also known as EFS control fields). See EFS formats for SORT, MERGE, INCLUDE, and OMIT control statements for further details. The EFS program must also return the final position, length, and sequence order. DFSORT uses the final position and length to create a list of offsets.

At Major Call 3, DFSORT sends the EFS program a list of offsets into a buffer. These offsets indicate where in the buffer the EFS program must have the EFS01 routine move the data indicated by the EFS control fields. See Extract buffer offsets list for further details. At Major Call 3, the EFS program must return the address of the EFS01 routine to DFSORT.

During the input phase, DFSORT calls the EFS01 routine for each input record. The EFS01 exit routine must move all data indicated by the EFS control fields, specified in the SORT or MERGE FIELDS operand, from the input record to the extract buffer area as specified by the offsets in the extract buffer offsets list. For each EFS control field, the total number of bytes moved by EFS01 into the buffer area is equal to the total number of bytes specified in the mm parameter of the altered SORT or MERGE operand. Records are ordered according to the altered ms parameter.

The EFS01 routine is called to extract all EFS control fields to the extract buffer area each time a new record is brought into the input phase.

DFSORT will do sort or merge processing using the data in the extract buffer, and will treat the data as binary data.