The following words are reserved in IBM DOS/VS, but not in ACUCOBOL-GT. They are, however, treated as reserved words by ACUCOBOL-GT when in IBM DOS/VS COBOL compatibility mode. You need to avoid using any of the IBM DOS/VS-specific reserved words as user-defined words.
| ACTUAL | DISPLAY-ST | SKIP |
| BEGINNING | EJECT | SORT-CORE-SIZE |
| C01 | ENDING | SORT-FILE-SIZE |
| C02 | ENTRY | SORT-MODE-SIZE |
| C03 | EXAMINE* | SORT-RETURN |
| C04 | EXTENDED-SEARCH | SUPPRESS |
| C05 | FILE-LIMIT | SYSPCH |
| C06 | MASTER-INDEX | SYSPUNCH |
| C07 | NOMINAL | TALLY |
| C08 | NOTE | TIME-OF-DAY* |
| C09 | OTHERWISE | TRACK-AREA |
| C10 | PASSWORD | TRANSFORM* |
| C11 | POSITIONING | WHEN-COMPILED |
| C12 | PROCESSING | WRITE-ONLY |
| COM-REG | S01 | WRITE-VERIFY |
| CORE-INDEX | S02 | |
| CSP | S03 | |
| CURRENT-DATE* | S04 | |
| CYL-INDEX | S05 | |
| CYL-OVERFLOW | SEEK |
* In VSC2 mode these words are NOT reserved. See Support for DOS/VS COBOL for details on this mode. Note that CURRENT-DATE is a valid function in any compatibility mode.