Open System Services System Calls Reference Manual (G06.25+, H06.03+)

Files limits(4)
POSIX-Defined Minimum Values
The symbolic constants in the following list are defined in the limits.h header file with values
specified by the POSIX.1 and POSIX.2 standards or in the POSIX.12 draft standard. These sym-
bolic names represent the most restrictive value for certain features. A portable application must
not require a larger value for correct operation. The HP implementation de
fines some of the
related symbolic constants to be less restrictive.
These values are the same in all POSIX-compliant implementations.
_POSIX_ARG_MAX
Maximum length in bytes of argument data to a function in the exec and
tdm_exec sets of functions, including environment data.
_POSIX_CHILD_MAX
Maximum number of simultaneous processes per real user ID.
_POSIX_FD_SETSIZE
Maximum number of file descriptors that the process can use with the select()
function.
_POSIX_HIWAT
Maximum number of bytes that a process can buffer on a socket for a send or
receive action.
_POSIX_LINK_MAX
Maximum number of links to a single file.
_POSIX_MAX_CANON
Maximum number of bytes in a terminal canonical input queue.
_POSIX_MAX_INPUT
Maximum number of bytes allowed in a terminal input queue.
_POSIX_NAME_MAX
Maximum number of bytes in a filename excluding the terminating null.
_POSIX_NGROUPS_MAX
Maximum number of simultaneous supplementary group IDs per process.
_POSIX_OPEN_MAX
Maximum number of files that a process can have open at a time.
_POSIX_PATH_MAX
Maximum number of bytes in a pathname including the terminating null.
_POSIX_PIPE_BUF
Maximum number of bytes that is guaranteed to be atomic when writing to a
pipe.
_POSIX_QLIMIT
Maximum number of connections that the process can queue on a single socket.
_POSIX_SSIZE_MAX
Maximum value that can be stored in an object of type ssize_t.
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