Most COBOL74 programs can be invoked in either of two ways: through process initiation statements or through the library linkage mechanism. If the program is invoked through the library linkage mechanism, the program automatically freezes and exports the PROCEDURE DIVISION. This automatic freeze occurs even though the program does not include a FREEZE statement or export declaration. For further information about COBOL library capabilities, refer to Using Libraries.

By contrast, a COBOL85 program can be initiated as a library only if it includes the $SET LIBRARYPROG compiler control statement or the CALL SYSTEM FREEZE statement.