linkage_name

    The name of a linkage to be defined.

 input=<>

    Register set that indicates those registers from which a routine
    with this linkage receives input values. This parameter is for
    documentation purposes only.

 output=<>

    Register set that indicates those registers to which a routine
    with this linkage assigns values that are returned to the
    routine's caller. Registers included in this register set are
    not saved and restored around the call.

 scratch=<>

    Register set that indicates registers that are used within a
    routine with this linkage. This parameter is for documentation
    purposes only.

 preserve=<>

    Register set that indicates those registers which a routine with
    this linkage will preserve. Registers included in this register
    set are not saved and restored around a call to the routine,
    since the called routine will perform that task.