For AMODE (31)

----+----1----+----2----+----3----+----4----+----5----+----6----+----7--
         GETMAIN ........           Obtain storage for parameter area
*                                   in primary address space.
         LR    R4,R1                Save parameter area address
         USING CUNBAPRM,R4          Make parameter area addressable
         XC    CUNBAPRM,CUNBAPRM    Init PARAMETER AREA TO BINARY 0
         LA    R15,CUNBAPRM_VER     Get Version
         ST    R15,CUNBAPRM_VERSION Store to parameter area
         LA    R15,CUNBAPRM_LEN     Initialize Length
         ST    R15,CUNBAPRM_LENGTH  Move to parameter area
         LA    R0,CUNBAPRM_TO_UPPER  Get conversion type
         STC   R0,CUNBAPRM_CONV_TYPE Store to parameter area
*
*        Supply source buffer pointer, length and ALET.
*        Supply target buffer pointer, length and ALET.
*        Supply DDA buffer pointer, length and ALET.
*        Note: A DDA is always required. The required DDA length is
*        defined by constant CUNBAPRM_DDA_REQ.
*
*        Fill all required fields of the parameter area.
         CALL  CUNLASE,((R4))  Call stub routine with CUNBAPRM
*                              address as argument.
         CUNBAIDF DSECT=YES    Provide Mappings (CUNBAPRM, return and
*                              reason codes, constants for version
*                              and length).

For AMODE (64)

----+----1----+----2----+----3----+----4----+----5----+----6----+----7--
         GETMAIN ........           Obtain storage for parameter area
*                                   in primary address space
         LR    R4,R1                Save parameter area address
         USING CUN4BAPR,R4          Make parameter area addressable
         XC    CUN4BAPR,CUN4BAPR    Init PARAMETER AREA TO BINARY 0
         LA    R15,CUN4BAPR_VER     Get Version
         ST    R15,CUN4BAPR_VERSION Version Store to parameter area
         LA    R15,CUN4BAPR_LEN     Initialize Length
         ST    R15,CUN4BAPR_LENGTH  Move to parameter area
         LA    R0,CUN4BAPR_TO_UPPER  Get conversion type
         ST    R0,CUN4BAPR_CONV_TYPE Store to parameter area
*
*        Supply source buffer pointer, length and ALET.
*        Supply target buffer pointer, length and ALET.
*        Supply DDA buffer pointer, length and ALET. 
*        Note: A DDA is always required. The required DDA length is
*        defined by constant CUN4BAPR_DDA_REQ.
*        Set flags
*
*        CALL CUN4LASE,((R4))  Call stub routine with CUN4BAPR
*                              address as argument.
*        CUN4BAID DSECT=YES    Provide Mappings (CUN4BAPR, return and
*                              reason codes, constants for version
*                              and length).