OPEN: BUFFERED Specifier

The BUFFERED specifier indicates run-time library behavior following WRITE operations. It takes the following form:

BUFFERED = bf

bf

Is a scalar default character expression that evaluates to one of the following values: 'NO' Requests that the run-time library send output data to the file system after each WRITE operation. 'YES' Requests that the run-time library accumulate output data in its internal buffer, possibly across several WRITE operations, before the data is sent to the file system. Buffering may improve run-time performance for output-intensive applications.

The default is 'NO'.

If BUFFERED='YES' is specified, the request may or may not be honored, depending on the output device and other file or connection characteristics.

For direct access, you should specify BUFFERED='YES', although using direct-access I/O to a network file system may be much slower.

If BLOCKSIZE and BUFFERCOUNT have been specified for OPEN, their product determines the size in bytes of the internal buffer. Otherwise, the default size of the internal buffer is 8192 bytes.

Note

On Windows systems, the default size of the internal buffer is 1024 bytes if compiler option fpscomp general is used.

The internal buffer will grow to hold the largest single record but will never shrink.