Many IBM® COBOL programs will compile without change under Enterprise COBOL.

The following programs, however, will need to be upgraded before compiling with Enterprise COBOL:
  • Programs compiled with the CMPR2 compiler option
  • Programs that have SOM-based object-oriented COBOL syntax
  • Programs that use words which are now reserved in Enterprise COBOL
  • Programs that have undocumented IBM COBOL extensions
  • Programs that contain the format 2 declarative syntax: USE...AFTER...LABEL PROCEDURE..., and optionally the syntax: GO TO MORE-LABELS.

For details, see Upgrading IBM COBOL source programs.