f_settag can be used to directly control basic file tagging for an opened file. The setting of the file tag may be immediate or deferred until the first write, depending upon the input parameters.

fd

The file descriptor (a number) for the file. It must be a regular file, FIFO, or character special file.

filetag

The name of a 4-byte hex variable describing the file tag. The CCSID (coded character set identifier) of the file tag occupies the first 2 bytes. For more information, see BPXYSTAT — Map the Response Structure for stat in z/OS UNIX System Services Programming: Assembler Callable Services Reference, or the C header file, stat.h in z/OS XL C/C++ Runtime Library Reference.