Open System Services System Calls Reference Manual (G06.29+, H06.08+, J06.03+)

Files limits(4)
_POSIX_TZNAME_MAX
Maximum number of bytes supported for the name of a time zone (not of the TZ
variable).
_POSIX2_BC_BASE_MAX
Maximum obase values allowed by the bc utility.
_POSIX2_BC_DIM_MAX
Maximum number of elements permitted in an array by the bc utility.
_POSIX2_BC_SCALE_MAX
Maximum scale value allowed by the bc utility.
_POSIX2_BC_STRING_MAX
Maximum length of a string constant accepted by the bc utility.
_POSIX2_COLL_WEIGHTS_MAX
Maximum number of weights that can be assigned to an entry of the
LC_COLLATE order keyword in the locale definition file.
_POSIX2_EXPR_NEST_MAX
Maximum number of expressions that can be nested within parentheses by the
expr utility.
_POSIX2_LINE_MAX
Unless otherwise noted, the maximum length, in bytes, of the input line to a util-
ity (from either the standard input file or another file), when the utility is
described as processing text files. The length includes room for the trailing new-
line character.
_POSIX2_RE_DUP_MAX
Maximum number of repeated occurrences of a regular expression permitted
when using the interval notation m,n.
Values Unknown at Compile Time
The following values are unknown at compile time and are therefore not defined in the limits.h
header file:
ARG_MAX Maximum length in bytes of argument data to a function in the exec, tdm_exec,
and tdm_spawn sets of functions. Use the sysconf() function to obtain this
value at run time.
CHILD_MAX Maximum number of simultaneous processes per real user ID. Use the sysconf()
function to obtain this value at run time.
IOV_MAX Maximum number of iovec structures that a process can use at a given time for
scatter or gather operations. Use the sysconf() function to obtain this value at
run time.
LINK_MAX Maximum value of a file’s link count. Use the pathconf() function to obtain this
value at run time.
MAX_CANON
Maximum number of bytes in a terminal canonical input line. Use the path-
conf() function to obtain this value at run time.
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