How the assembler works (6)

Checking for reentrant code

I wrote about how you could make your program reentrant some blog posts ago. The assembler can actually help you check for non-reentrant code.

PRINT GEN             PGM4     RSECT                 PGM4     RMODE ANY                      ENTRY PGM4                     BASR  11,0                     USING *,11                     MVC   NAME,=CL8'PGM4'           B     RETURN          NAME     DS    CL8             RETURN   RETURN RC=0                    LTORG                          END                    PGM4     BINDER REUS=RENT               END

Non-reentrant code

All you have to do is replace CSECT with RSECT on the first line and tell the Linkage Editor, that the module must be Link Edited to reentrant.

Loc  Object Code    Addr1 Addr2  Stmt   Source Statement                                                     1          PRINT GEN               000000                00000 00028     2 PGM4     RSECT                                                         3 PGM4     RMODE ANY                                                     4          ENTRY PGM4              000000 0DB0                           5          BASR  11,0                               R:B  00002           6          USING *,11              000002 D207 B00A B01E 0000C 00020     7          MVC   NAME,=CL8'PGM4'   ** ASMA036W Reentrant check failed                                       ** ASMA435I Record 7 in EXJEL.EXJEL004.JOB07544.D0000101.? on volume:    000008 47F0 B012            00014     8          B     RETURN            00000C                                9 NAME     DS    CL8                                                    10 RETURN   RETURN RC=0             000014                               12+RETURN   DS    0H                000014 41F0 0000            00000    13+         LA    15,0(0,0)         000018 07FE                          14+         BR    14                000020                               15          LTORG                   000020 D7C7D4F440404040              16                =CL8'PGM4'                                             17          END

Assembler list with reentrant error.

The result is an error where you do not respect the rules for reentrant coding:

** ASMA036W Reentrant check failed