Extended File Status Codes

The ANSI'74 and ANSI'85 file status conventions are augmented with extended file status codes. Extended file status codes have the character "9" as the first byte of the file status. The second byte is a binary (COMP-X) number, which is equivalent to a run-time system error number.

Extended file status codes are written as 9/nnn where nnn is the binary number in the second byte.

For example, if you are writing a file to disk and the disk runs out of space, the ANSI'74 file status would be a "30", which translates into the error message:

Permanent error - no other information is available

This error message is very general; a "permanent error" could mean that the disk has failed, or that the disk drive door is open. So, rather than return a generic file status, this COBOL system returns an extended file status of 9/007, that is, the character "9", in the first byte, and the binary value 7 in the second, meaning "disk full".

When using ANSI'74 or ANSI'85 file status codes, the run-time system returns extended file status codes if the extended file status code is more specific.

The example code that follows illustrates how to redefine a standard file status so that it can be used as an extended file status. Assume for this example that the input file does not exist - when the OPEN INPUT statement is executed, a file status of 9/013 ("File not found") is returned.

     select in-file
         assign to "user.dat".
         file status is file-status.
        ...
 working-storage section.
 01 file-status.
     05 status-key-1             pic x.
     05 status-key-2             pic x.
     05 status-key-2-binary redefines status-key-2 
                                 pic 99 comp-x.
     ...
 procedure division.
     open input in-file
     if file-status not = "00"
         if status-key-1 = "9"
             if status-key-2-binary = 13
                 display "File not found"
        ...

To display the extended file status code, move the second byte of the file status data item to a display field large enough to hold the maximum value 255:

     select in-file
         assign to "user.dat"
         file status is file-status.
 ...
 working-storage section.
 01 ans74-file-status.
     05 status-key-1              pic x.
     05 status-key-2              pic x.
     05 status-key-2-binary redefines status-key-2 
                                  pic 99 comp-x.
 01 display-ext-status
     05 filler                    pic xx value "9/"
     05 display-key 2             pic 999
     ...
 procedure division.
     open input in-file
     if file-status not = "00"
         display "Error. File status =" with no advancing
         if status-key-1 = "9"
             move status-key-2-binary to display-key-2
             display display-ext-status
         else
             display file-status
         end-if
     end-if