DECOVF: PROCEDURE OPTIONS (MAIN);

    %INCLUDE LIB$DEC_OVER;

    DECLARE DISABLE FIXED BINARY (31) INITIAL (0) STATIC READONLY;
    DECLARE OLD_DV FIXED BINARY (31);
    DECLARE (A,B) FIXED DECIMAL (4,2);

    ON FIXEDOVERFLOW PUT SKIP LIST ('    Overflow detected');

    PUT LIST ('In procedure MAIN');

    A = 99.99;

    /* Temporarily disable decimal overflow */
    OLD_DV = LIB$DEC_OVER (DISABLE);

    /* Does not raise FIXEDOVERFLOW */
    B = A + 2;

    BEGIN;

        PUT SKIP LIST ('In BEGIN block');

        /* Raises FIXEDOVERFLOW */
        B = A + 2;

        CALL Q;

     Q: PROCEDURE;

            PUT SKIP LIST ('In procedure Q');

            /* Raises FIXEDOVERFLOW */
            B = A + 2;

            END Q;

        END /* Begin */;

    PUT SKIP LIST ('Back in procedure MAIN');

    /* Restore the old overflow flag */
    OLD_DV = LIB$DEC_OVER (OLD_DV);

    /* Raises FIXEDOVERFLOW */
    B = A + 2;

    END DECOVF;