COBOL Manual for TNS/E Programs (H06.08+, J06.03+)

Usage Considerations:
• SIZE ERROR Phrase and TRAP2 Directive
NOTE: The ECOBOL compiler, which has traps set by default, ignores the TRAP2 directive
and issues a warning.
The SIZE ERROR phrase catches size errors in COMPUTATIONAL arithmetic that the TRAP2
directive (which is the default) does not; however, the SIZE ERROR phrase generates more
code than the TRAP2 directive does.
In Example 66, C=A+B causes a size error that the TRAP2 directive does not catch, but that
the SIZE ERROR phrase does catch.
Example 66 SIZE ERROR Phrase and TRAP2 Directive
WORKING-STORAGE SECTION.
77 A PIC 99 COMP VALUE 99.
77 B PIC 99 COMP VALUE 88.
77 C PIC 99 COMP.
77 D PIC 99 COMP.
PROCEDURE DIVISION.
...
* TRAP2 directive does not catch this size error:
COMPUTE C = A + B.
COMPUTE D = C - B.
DISPLAY D.
* ON SIZE ERROR phrase catches this size error:
COMPUTE C = A + B
ON SIZE ERROR DISPLAY "Too Big"
NOT ON SIZE ERROR DISPLAY "Acceptable".
...
• COMPUTATIONAL Data Items
If an arithmetic computation stores a value in a COMPUTATIONAL data item, and the decimal
representation of that value exceeds the number of decimal places in the item’s PICTURE clause
(as in C = A + B in the preceding example), a later attempt to use that value (as in D = C - B
in the preceding example) can cause arithmetic overflow.
HP COBOL can retrieve a number larger than 9,999 from a PICTURE S9(4) COMPUTATIONAL
field (even though the storage unit is 2 bytes and can therefore accommodate values from
-32,767 through +32,767), but arithmetic overflow is likely.
The largest value HP COBOL can use in a 4-byte COMPUTATIONAL item is 999,999,999
(not 2,147,483,647).
The largest value HP COBOL can use in an 8-byte COMPUTATIONAL item is
999,999,999,999,999,999 (not 9,223,372,036,854,775,807).
If you need the full capacity of 2-byte, 4-byte, and 8-byte storage, describe the item as USAGE
NATIVE-2, NATIVE-4, or NATIVE-8 (with no PICTURE) or COMPUTATIONAL-5.
• SIZE ERROR and Multiple Results
When a statement includes more than one receiving item, the decision to assign a result value
or cause a size error condition is determined independently for each such item; therefore, if
the size error condition does not occur for a particular receiving item, that item is assigned
its correct result value even when the size error condition exists for one or more other receiving
items of the same statement (unless the run terminates abnormally because of an arithmetic
overflow).
Common Phrases 245