IDENTIFICATION DIVISION.
            PROGRAM-ID. FIB.
        DATA DIVISION.
        WORKING-STORAGE SECTION.
        01 STACK-SPACE.
            05 STACK PIC 9(18) USAGE IS COMP
                OCCURS 1000 TIMES
                INDEXED BY SP.

        01 LR PIC 9(2) USAGE IS COMP.
        01 I PIC 9(18) USAGE IS COMP.
        01 N PIC 9(18) USAGE IS COMP.
        01 R PIC 9(18) USAGE IS COMP.

        01 DISP-A PIC Z(1)9.
        01 DISP-B PIC Z(8)9.

        PROCEDURE DIVISION.

        MAIN.
            SET I TO 1.

        MAIN-LOOP.
            SET N TO I.
            SET LR TO 4.
            GO TO FIB.
        L4.
            MOVE I TO DISP-A.
            MOVE R TO DISP-B.
            DISPLAY "FIB("DISP-A") = "DISP-B.
            ADD 1 TO I.
            IF I LESS THAN OR EQUAL TO 32 THEN GO TO MAIN-LOOP.
            STOP RUN.

        FIB.
            IF N IS LESS THAN 2 THEN GO TO L3.

            SET STACK(SP) TO LR.
            SET SP UP BY 1.
            SET STACK(SP) TO N.
            SET SP UP BY 1.

            SUBTRACT 2 FROM N.
            SET LR TO 1.
            GO TO FIB.
        L1.
            SET N TO STACK(SP - 1).
            SET STACK(SP - 1) TO R.

            SUBTRACT 1 FROM N.
            SET LR TO 2.
            GO TO FIB.
        L2.
            COMPUTE R = R + STACK(SP - 1).
            SET LR TO STACK(SP - 2).
            SET SP DOWN BY 2
            GO TO RET.
            
        L3.
            SET R TO N.
            GO TO RET.


        RET.
            GO TO L1 L2 L3 L4 DEPENDING ON LR.