Example of assembler main routine

Figure 1 shows a simple assembler main routine. In the example, the Language Environment environment is established, a message showing control is received in the routine, and the Language Environment environment terminates with a zero return code passed in R15 to the invoker.

If you write an assembler main routine, nominate the routine as a load module entry point using the END statement, as Figure 1 shows. Otherwise, you must explicitly declare the routine as the entry point at link-edit time.

Figure 1. Example of a simple main assembler routine

*COMPILATION UNIT: LEASMMN
* ===================================================================
*
*        A simple main assembler routine that brings up the
*        LE/370 environment, prints a message in the main routine,
*        and returns with a return code of 0, modifier of 0.
*
* ===================================================================
MAIN     CEEENTRY PPA=MAINPPA
*
*        Invoke CEEMOUT to issue a message for us
*
         CALL  CEEMOUT,(STRING,DEST,0),VL   Omitted feedback code
*
*   Terminate the LE/370 environment and return to the caller
*
         CEETERM  RC=0,MODIFIER=0
* ====================================================================
*              CONSTANTS AND WORKAREAS
* ====================================================================
*
DEST     DC    F'2'
STRING   DC    Y(STRLEN)
STRBEGIN DC    C'In the main routine'
STRLEN   EQU   *-STRBEGIN
MAINPPA  CEEPPA  ,                Constants describing the code block
         CEEDSA  ,                Mapping of the dynamic save area
         CEECAA  ,                Mapping of the common anchor area
         END   MAIN               Nominate MAIN as the entry point