Invoking the assembler dynamically

You can invoke High Level Assembler from a running program using the CALL, LINK, XCTL, or ATTACH system macro instructions.

Note: If the program that invokes the High Level Assembler is APF-authorized, then ensure that the High Level Assembler product resides in an Authorized Program Facility (APF) authorized library.

When you use CALL, LINK, or ATTACH, you can supply:

The assembler options.
The ddnames of the data sets to be used during processing.

If you use XCTL, you cannot pass options to the assembler. The assembler uses the installation default options. Table 1 shows how to invoke the assembler dynamically.

Table 1. Invoking the assembler dynamically
Name	Operation	Operand
symbol	`CALL`	>>-ASMA90,(optionlist-+-------------+-),VL--------------------->< '-,ddnamelist-'
	`LINK` or `ATTACH`	>>-EP=ASMA90,PARAM=(optionlist-+-------------+-),VL=1---------->< '-,ddnamelist-'

ASMA90

The load module name and entry point to invoke the assembler. ASMA90 must be invoked in 31-bit addressing mode.

EP

Specifies the symbolic name of the assembler load module and entry point.

PARAM

Specifies, as a sublist, address parameters to be passed from the program to the assembler. The first word in the address parameter list (optionlist) contains the address of the option list. The second word (ddnamelist) contains the address of the ddname list.

optionlist

Specifies the address of a variable-length list containing the options. The address of an option list must be provided even if no options are required.

The option list must begin on a halfword boundary. The first two bytes contain the number of bytes in the remainder of the list. If no options are specified, the count must be zero. The option list is free form, with each field separated from the next by a comma. No spaces should appear in the list, except within the string specified for the EXIT or SYSPARM options, providing the string is enclosed within apostrophes.

ddnamelist

Specifies the address of a variable-length list containing alternative ddnames for the data sets used during assembler processing. If standard ddnames are used, this operand can be omitted.

The ddname list must begin on a halfword boundary. The first two bytes contain the number of bytes in the remainder of the list. Each name of less than eight bytes must be left-aligned and padded to eight bytes with spaces. If an alternative ddname is omitted, the standard name is assumed. If the name is omitted within the list, the eight-byte entry must contain binary zeros. Names can be omitted from the end merely by shortening the list. The sequence of the eight-byte entries in the ddname list is as follows:

Entry: Alternative
1: SYSLIN
2: Not applicable
3: Not applicable
4: SYSLIB
5: SYSIN
6: SYSPRINT
7: SYSPUNCH
8: SYSUT1
9: Not applicable
10: Not applicable
11: Not applicable
12: SYSTERM
13: Not applicable
14: Not applicable
15: Not applicable
16: SYSADATA
17: Not applicable
18: Not applicable
19: Not applicable
20: ASMAOPT

Overriding ddname: Any overriding ddname specified when High Level Assembler was installed, occupies the corresponding position in the above list. The overriding ddname can also be overridden during invocation. For example, if SYSWORK1 replaced SYSUT1, it occupies position 8 in the above list. However, SYSWORK1 can be overridden by another name during invocation.

VL

specifies that the sign bit is to be set to 1 in the last word of the parameter address list. VL must be specified for the CALL macro and VL=1 for the LINK or ATTACH macros.

Figure 1. Sample program to call the assembler dynamically

DYNAMICM CSECT
DYNAMICM RMODE  24
DYNAMICM AMODE  ANY
BEGIN    SAVE   (14,12)
         USING  BEGIN,15
         ST     13,SAVEAREA+4
         LA     13,SAVEAREA
         CALL   ASMA90,(OPTIONS),VL
         L      13,SAVEAREA+4
         RETURN (14,12)
SAVEAREA DS     18F
OPTIONS  DC     Y(OPTIONSL)
OPTS     DC     C'XREF(SHORT)'
OPTIONSL EQU    *-OPTS
         END