Decimal length and precision errors

If a decimal value is passed with an incorrect decimal length and precision (either too long or too short), a decimal data error (MCH1202) occurs when the variable is referred to. In the following examples, the numeric constant is passed as LEN(15 5), but is declared in the called procedure or program as LEN(5 2). Numeric constants are always passed as packed decimal (15 5).

CALL PGMA PARM(123)     /* CALLING PROG */
 
PGM PARM(&A)                  /* PGMA */
DCL &A *DEC (5 2)
.
.
.
IF (&A *GT 0) THEN(...) /* MCH1202 OCCURS HERE */

If a decimal variable had been declared with LEN(5 2) in the calling program or procedure and the value had been passed as a variable instead of as a constant, no error would occur.

If you need to pass a numeric constant to a procedure or program and the procedure or program is expecting a value with a length and precision other than 15 5, the constant can be coded in hexadecimal format. The following CALL command shows how to pass the value 25.5 to a program variable that is declared as LEN(5 2):

CALL PGMA PARM(X'02550F')

If a decimal value is passed with the correct length but with the wrong precision (number of decimal positions), the receiving procedure or program interprets the value incorrectly. In the following example, the numeric constant value (with length (15 5)) passed to the procedure is handled as 25124.00.

CALL PGMA PARM(25.124)  /* CALLING PGM */
 
PGM PARM(&A)            /* PGMA */
DCL &A *DEC (15 2)      /* LEN SHOULD BE 15 5*/
.
.
.
ENDPGM

These errors occur when the variable is first referred to, not when it is passed or declared. In the next example, the called program does not refer to the variable, but instead places a value (of the detected wrong length) in the variable returned to the calling program. The error is not detected until the variable is returned to the calling program and first referred to. This kind of error can be especially difficult to detect.

PGM           /* PGMA */
DCL &A *DEC (7 2)
CALL PGMB PARM(&A)  /* (7 2) PASSED TO PGMB */
IF (&A *NE 0)  THEN(...)  /* *MCH1202 OCCURS HERE */
.
.
.
ENDPGM

PGM PARM(&A) /* PGMB */
DCL &A *DEC (5 2)        /* WRONG LENGTH */
.
.
.
 CHGVAR &A (&B-&C)      /* VALUE PLACED in &A */
RETURN
When control returns to program PGMA and &A is referred to, the error occurs.