To allow user exits called by Blockset or Peerage/Vale to reside above or below 16MB virtual, and use either 24-bit, 31-bit or 64-bit addressing, DFSORT supplies these features:

• To ensure that DFSORT enters your user exit with the correct addressing mode, you must observe these rules:
  • If the user exit name is specified in a MODS control statement, the user exit is entered with the addressing mode indicated by the linkage editor attributes of the routine (for example, 31-bit addressing in effect if AMODE 31 is specified).
  • If the address of the exit is passed to DFSORT (preloaded exit) via the 24-bit list, the user exit is entered with 24-bit addressing in effect.
  • If the address of the user exit is passed to DFSORT via the extended parameter list (preloaded exit), the user exit is entered with 24-bit addressing in effect if bit 0 of the user exit address in the list is 0 or with 31-bit addressing in effect if bit 0 of the user exit address in the list is 1.
  • If the address of the user exit is passed to DFSORT via the 64-bit parameter list (preloaded exit), the user exit is entered with the addressing mode in effect as specified by the appropriate flag in byte 8 or 9 of the parameter list as follows:

    Table 1. Addressing Mode Flags for Exits in 64-bit Parameter List

    Byte	Bit	Meaning when on
    8	0	Enter E15 or E32 in AMODE 24
    	1	Enter E15 or E32 in AMODE 31
    	2	Enter E15 or E32 in AMODE 64
    	3	Enter E35 in AMODE 24
    	4	Enter E35 in AMODE 31
    	5	Enter E35 in AMODE 64
    	6	Enter E18 in AMODE 24
    	7	Enter E18 in AMODE 31
    9	1	Enter E39 in AMODE 24
    	2	Enter E39 in AMODE 31

• User exits can return to DFSORT with either 24-bit, 31-bit, or 64-bit addressing in effect. The return address that DFSORT placed in register 14 must be used.
  Note: For a conventional merge or tape work data set sort application, user exits:

  • must reside below 16MB virtual
  • must use 24-bit addressing mode
  • must not use a user exit address constant.