Initiates the processing of a file. It also performs checking and writing of labels and other I/O operations.
| Opcode | Operation | File Types |
|---|---|---|
| 00 | OPEN INPUT | L S R I |
| 01 | OPEN OUTPUT | L S R I |
| 02 | OPEN I-O | L S R I |
| 03 | OPEN EXTEND | L S R I |
| 04 | OPEN INPUT WITH NO REWIND | L S |
| 05 | OPEN OUTPUT WITH NO REWIND | L S |
| 08 | OPEN INPUT REVERSED | L S |
Input Fields:
| Filename area | |
| Key definition block | |
| fcd-organization | File organization |
| fcd-access-mode | Access mode |
| fcd-open-mode | Open mode |
| fcd-name-length | Length of filename |
| fcd-lock-mode | Lock mode flags |
| fcd-other-flags | Other flags |
| fcd-file-format | File format |
| fcd-max-rec-length | Maximum record length |
| fcd-recording-mode | Recording mode |
| fcd-min-rec-length | Minimum record length |
| fcd-filename-address | Pointer to the filename area |
| fcd-key-def-address | Pointer to the key definition block (I) |
| fcd-data-compress | Data compression |
| fcd-locktypes | Type of file locks |
Output Fields:
| fcd-file status | File status |
| fcd-open-mode | Open mode |
| fcd-handle | Pointer to the file; use for all subsequent accesses to this file |
Comments:
You must have set up a key definition block for this file if it is an indexed file.
You can assign several FCDs to the same physical file and have them all open at the same time. The operating system counts it as just one open file. The physical file is not closed until every logical file assigned to it has been closed.