I-O status

The status of each access operation performed on a file is stored by the runtime system in specific data items, which can be assigned to every file in the program. These items, which are specified by using the FILE STATUS clause, provide information on

• whether the I-O operation was successful, and

• the type of errors that may have occurred.

This data can be evaluated (by USE procedures in the DECLARATIVES, for example) and used by the program to analyze I-O errors. As an extension to Standard COBOL, COBOL2000 provides the option of including the key of the DMS error messages in this analysis, thus allowing a finer differentiation between different causes of errors. The FILE STATUS clause is specified in the FILE-CONTROL paragraph of the Environment Division. Its format is (see “COBOL2000 Reference Manual” [1]):

---

FILE STATUS IS data-name-1 [data-name-2]

---

where data-name-1 and data-name-2 (if specified) must be defined in the WORKING-STORAGE SECTION or the LINKAGE SECTION. The following rules apply with regard to the format and possible values for these two items:

data-name-1

• must be declared as a two-byte alphanumeric data item, e.g.

  01 data-name-1      PIC X(2).

• contains a two-character numeric status code following each access operation on the associated file. The table provided at the end of this section lists all such codes together with their meanings.

data-name-2

• must be declared as a 6-byte group item with the following format:

  01 data-name-2.
     02 data-name-2-1        PIC 9(2) COMP.
     02 data-name-2-2        PIC X(4).
  

• is used for storing the DMS error code for the relevant I-O status. Following each access operation on the associated file, data-name-2 contains a value that directly depends on the content of data-name-1. The relationship between the values is shown in the table below:

  Is contents of data-name-1 not equal to 0?	Is DMS code not equal to 0?	Value of data-name-2-1	Value of data-name-2-2
  no	no	undefined	undefined
  yes	no	0	undefined
  yes	yes	64	DMS code of the associated error message

  The DMS codes and the associated error messages are given in “Introductory Guide to DMS” [4].

I-O status	Meaning
	Execution successful
00	The I-O statement terminated normally. No further information regarding the I-O operation is available.
04	Record length conflict: A READ statement was executed successfully, but the length of the record which was read does not lie within the limits specified in the record description for the file.
05	Successful OPEN INPUT/I-O/EXTEND for a file with the OPTIONAL phrase in the SELECT clause that was not present at the time of execution of the OPEN statement.
	Execution unsuccessful: AT END condition
10	An attempt was made to execute a READ statement. However, no next logical record was available, since the end-of-file was encountered (sequential READ). A first attempt was made to execute a READ statement for a non-existent file with the specification OPTIONAL. A first attempt was made to execute a READ statement for a non-existent file which is specified as OPTIONAL.
14	An attempt was made to execute a READ statement. However, the data item described by RELATIVE KEY is too small to accommodate the relative record number. (sequential READ).
	Execution unsuccessful: invalid key condition
22	Duplicate key An attempt was made to execute a WRITE statement with a key for which there is already a record in the file.
23	Record not located or zero record key An attempt was made (using a READ, START, DELETE or REWRITE statement with a key) to access a record not contained in the file, or the access was effected with a zero record key.
24	Boundary values exceeded. An attempt was made to execute a WRITE statement beyond the system-defined boundaries of a relative file (insufficient secondary allocation in the FILE command), or a WRITE statement is attempted in sequential access mode with a relative record number so large that it does not fit in the data item defined with the RELATIVE KEY phrase.
	Execution unsuccessful: permanent error
30	No further information regarding the I-O operation is available.
35	An attempt was made to execute an OPEN INPUT/I-O statement for a nonexistent file.
37	An OPEN statement is attempted on a file that cannot be opened due to the following conditions: OPEN OUTPUT/I-O/EXTEND on a write-protected file (password, RETPD in catalog, ACCESS=READ in catalog) OPEN INPUT on a read-protected file (password)
38	An attempt was made to execute an OPEN statement for a file previously closed with the LOCK phrase.
39	The OPEN statement was unsuccessful as a result of one of the following conditions: One or more of the operands ACCESS-METHOD, RECORD-FORMAT or RECORD-SIZE were specified in the ADD-FILE-LINK command with values which conflict with the corresponding explicit or implicit program specifications. The catalog entry of the FCBTYPE operand for an input file does not match the corresponding explicit or implicit program specification or the specification in the ADD-FILE-LINK command. Variable record length has been defined for a file that is to be processed using the UPAM access method of the DMS.
	Execution unsuccessful: logical error
41	An attempt was made to execute an OPEN statement for a file which was already open.
42	An attempt was made to execute a CLOSE statement for a file which was not open.
43	For ACCESS MODE IS SEQUENTIAL: The most recent I-O statement executed prior to a DELETE or REWRITE statement was not a successfully executed READ statement.
44	Record length limits exceeded: An attempt was made to execute a WRITE or REWRITE statement, but the length of the record does not lie within the limits defined for the file.
46	An attempt was made to execute a sequential READ statement for a file in INPUT or I-O mode. However, there is no valid next record since: the preceding START statement terminated abnormally, or the preceding READ statement terminated abnormally without causing an AT END condition. the preceding READ statement caused an AT END condition.
47	An attempt was made to execute a READ or START statement for a file not in INPUT or I-O mode.
48	An attempt was made to execute a WRITE statement for a file that on sequential access is not in OUTPUT or EXTEND mode on random or dynamic access is not in OUTPUT or I-O mode.
49	An attempt was made to execute a DELETE or REWRITE statement for a file not in I-O mode.
	Other conditions with unsuccessful execution
90	System error; no further information regarding the cause is available.
91	System error; OPEN error
93	For shared update processing only (see section "Shared updating of files (SHARED-UPDATE)"): The I-O statement could not terminate normally because a different task is accessing the same file, and the access operations are incompatible.
94	For shared update processing only (see section "Shared updating of files (SHARED-UPDATE)"): deviation from call sequence READ - REWRITE/DELETE.
95	Incompatibility between values specified in the BLOCK-CONTROL-INFO or BUFFER-LENGTH operand of the ADD-FILE-LINK command and the file format, block size, or the format of the used volume.
96	READ PREVIOUS is not supported for modules that were compiled with COBRUN ENABLE-UFS-ACCESS=YES or the file should be processed with the DMS UPAM access mode.

Table 29: I-O status for relative files