Effect of CLOSE statement on file types
If the SELECT OPTIONAL clause is specified in the file-control entry for a file, and the file is not available at run time, standard end-of-file processing is not performed. For QSAM files, the file position indicator and current volume pointer are unchanged.
Files are divided into the following types:
- Non-reel/unit
- A file whose input or output medium is such that rewinding, reels, and units have no meaning. All VSAM files are of non-reel/unit file types. QSAM files can be of non-reel/unit file types.
- Sequential single volume
- A sequential file that is contained entirely on one volume. More than one file can be contained on this volume. All VSAM files are single volume. QSAM files can be single volume.
- Sequential multivolume
- A sequential file that is contained on more than one volume. QSAM files are the only files that can be multivolume. The concept of volume has no meaning for VSAM files.
The permissible combinations of CLOSE statement phrases are shown in the following tables:
- For sequential files: Sequential files and CLOSE statement phrases
- For indexed and relative files: Table 2
- For line-sequential files: Table 3
CLOSE statement phrases | Non-reel/ unit | Sequential single-volume | Sequential multivolume |
---|---|---|---|
CLOSE | C | C, G | A, C, G |
CLOSE REEL/UNIT | F | F, G | F, G |
CLOSE REEL/UNIT WITH NO REWIND | F | B, F | B, F |
CLOSE REEL/UNIT FOR REMOVAL | D | D | D |
CLOSE WITH NO REWIND | C, H | B, C | A, B, C |
CLOSE WITH LOCK | C, E | C, E, G | A, C, E, G |
CLOSE statement phrases | Action |
---|---|
CLOSE | C |
CLOSE WITH LOCK | C,E |
CLOSE statement phrases | Action |
---|---|
CLOSE | C |
CLOSE WITH LOCK | C,E |
Key | Actions taken |
---|---|
A | Previous volumes unaffected Input and input-output files: Standard volume-switch processing is performed for all previous volumes (except those controlled by a previous CLOSE REEL/UNIT statement). Any subsequent volumes are not processed. Output files: Standard volume-switch processing is performed for all previous volumes (except those controlled by a previous CLOSE REEL/UNIT statement). |
B | No rewinding of current reel: The current volume is left in its current position. |
C | Close file Standard system closing procedures are performed. |
D | Volume removal: Treated as a comment. |
E | File lock: The compiler ensures that this file cannot be opened again during this execution of the object program. If the file is a tape unit, it will be rewound and unloaded. |
F | Close volume Input and input-output files: If the current reel/unit is the last or only reel/unit for the file or if the reel is on a non-reel/unit medium, no volume switching is performed. If another reel/unit exists for the file, the following operations are performed: a volume switch, and the first record on the new volume is made available for reading. If no data records exist for the current volume, another volume switch occurs. Output (reel/unit media) files: The following operations are performed: a volume switch. The next executed WRITE statement places the next logical record on the next direct access volume available. A close statement with the REEL phrase does not close the output file; only an end-of-volume condition occurs. Output (non-reel/unit media) files: Execution of the CLOSE statement is considered successful. The file remains in the open mode and no action takes place except that the value of the I-O status associated with the file is updated. |
G | Rewind: The current volume is positioned at its physical beginning. |
H | Optional phrases ignored: The CLOSE statement is executed as if none of the optional phrases were present. |