EFS01 and EFS02 function description

Each DFSORT control statement describes to DFSORT the type of operation to be performed on input data. Through the EFS interface, DFSORT enables an EFS program to provide user exit routines to perform functions beyond the capabilities of DFSORT control statements.

The EFS program can provide user exit routine EFS01 to supplement the function of the DFSORT SORT/MERGE control statements and can provide user exit routine EFS02 to perform the function of the DFSORT INCLUDE/OMIT control statements.

When preparing your EFS program exit routines, remember:

The routines must follow standard linkage conventions.
The general registers used by DFSORT for linkage and communication of parameters follow operating system conventions (see Figure 1).
The routines must use the described interfaces (see EFS01 parameter list and EFS02 parameter list).

Figure 1. DFSORT Register Convention

Register: Use
1: DFSORT places the address of a parameter list in this register.
13: DFSORT places the address of a standard save area in this register. The area can be used to save contents of registers used by the EFS program exit routine. The first word of the area contains the characters SM1 in its three low-order bytes.
14: Contains the address of DFSORT return point.
15: Contains the address of the EFS program exit routine. This register can be used as the base register for EFS program exit routine. This register is also used by the EFS program exit routine to pass return codes to DFSORT.