Status group

OAPPEND

Specifies that MVS™ sets the file offset to the end of the file before each write, so that data is written at the end of the file.

OCREAT

Specifies that:

If the file does not exist, the system is to create it. If a directory specified in the pathname does not exist, one is not created, and the new file is not created.
If the file already exists and OEXCL was not specified, the system allows the program to use the existing file.
If the file already exists and OEXCL was specified, the system fails the allocation and the job step.

OEXCL

Specifies that:

If the file does not exist, the system is to create it.
If the file already exists, the system fails the allocation and the job step.

The system ignores OEXCL if OCREAT is not also specified.

ONOCTTY

Specifies that if the PATH parameter identifies a terminal device, opening of the file does not make the terminal device the controlling terminal for the process.

ONONBLOCK

Specifies the following, depending on the type of file:

For a FIFO special file:
- With ONONBLOCK specified and ORDONLY access: An open() function for reading-only returns without delay.
- With ONONBLOCK not specified and ORDONLY access: An open() function for reading-only blocks (waits) until a process opens the file for writing.
- With ONONBLOCK specified and OWRONLY access: An open() function for writing-only returns an error if no process currently has the file open for reading.
- With ONONBLOCK not specified and OWRONLY access: An open() function for writing-only blocks (waits) until a process opens the file for reading.
For a character special file that supports nonblocking open:
- If ONONBLOCK is specified: An open() function returns without blocking (waiting) until the device is ready or available. Device response depends on the type of device.
- If ONONBLOCK is not specified: An open() function blocks (waits) until the device is ready or available.

Specification of ONONBLOCK has no effect on other file types.

OSYNC

Specifies that the system is to move data from buffer storage to permanent storage before returning control from a callable service that performs a write.

OTRUNC

Specifies that the system is to truncate the file length to zero if all the following are true:

The file specified on the PATH parameter exists.
The file is a regular file.
The file successfully opened with ORDWR or OWRONLY.

The system does not change the mode and owner. OTRUNC has no effect on FIFO special files or character special files.