Looks like subject to remove. # grep -rsp "_POSIX_THREAD_THREADS_MAX" /usr/src/ /usr/src/contrib/netbsd-tests/include/t_limits.c:#ifdef _POSIX_THREAD_THREADS_MAX /usr/src/contrib/netbsd-tests/include/t_limits.c: { "_POSIX_THREAD_THREADS_MAX", _POSIX_THREAD_THREADS_MAX, 64 }, /usr/src/include/limits.h:#define _POSIX_THREAD_THREADS_MAX 64 /usr/src/share/man/man3/pthread_join.3:[_POSIX_THREAD_THREADS_MAX]. /usr/src/usr.bin/getconf/limits.gperf:_POSIX_THREAD_THREADS_MAX, _POSIX_THREAD_THREADS_MAX
Thanks for the report! I think we're supposed to keep that because it's part of POSIX.1. Old applications in the wild might need it. Please explain further if you think this is an error. https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/limits.h.html
At least it can be removed from man and getconf. I have no idea how to interpret it in man pthread_join.