With OS/VS COBOL, you must maintain addressability to storage areas not contained within the WORKING-STORAGE SECTION of the COBOL CICS program. To satisfy program requests, an OS/VS COBOL program must keep track of storage area addresses allocated by CICS to manipulate Base locator for LINKAGE-SECTION (BLL) cells within the application program.
In Enterprise COBOL, and the associated support within CICS, this manipulation is no longer necessary. Therefore, when you upgrade from OS/VS COBOL to Enterprise COBOL, you must convert such programs. (If the COBOL CICS program does not manipulate its BLL cells addressing, conversion is not necessary.)