COBOL: Increment a given date by one month

The below code snippet can increment a given date by one month

01 MONTH-END-DD PIC X(24) VALUE '312831303130313130313031'.

01 TBL-MONTH-END REDEFINES MONTH-END-DD.

   03 TBL-MONTH-END-DAY OCCURS 12 TIMES.

      05 TBL-MONTH-END-DD PIC 9(02).

01 WS-DATE.

   02 YYYY PIC 9(4).

   02 MM PIC 99.

   02 DD PIC 99.

MOVE INPUT-DATE TO WS-DATE

IF MM = 12

   ADD +1 TO YYYY

   MOVE 1 TO MM

ELSE

   ADD +1 TO MM

END-IF

IF ( FUNCTION MOD (YYYY, 400) = 0) OR

   ( FUNCTION MOD (YYYY, 4) = 0 AND

     FUNCTION MOD (YYYY, 100) NOT = 0 )

     MOVE '29' TO TBL-MONTH-END-DD (3:2)

ELSE

     MOVE '28' TO TBL-MONTH-END-DD (3:2)

END-IF

IF DD > TBL-MONTH-END-DAY (MM)

   MOVE TBL-MONTH-END-DAY (MM) TO DD

END-IF