MB_LEN_MAX - maximum multibyte length of a character across all locales
The MB_LEN_MAX macro is the upper bound for the number of bytes needed
to represent a single wide character, across all locales.
A constant integer greater than zero.
The entities MB_LEN_MAX and sizeof(wchar_t) are totally unrelated. In
glibc, MB_LEN_MAX is typically 6 while sizeof(wchar_t) is 4.
This page is part of release 3.24 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.