Hi, Apologies if I'm double posting this, but I have not seen my original post to list appear in the archives, so I'm assuming it got lost in cyberspace ! Hi, As per the performance docs, I am trying to set the recommended ULIMIT of 8192 stacksize on a 64 bit machine. I am using the current version of Freeswitch (as pulled off GIT yesterday, Friday). I am running Scientific Linux 6.1 : Linux 2.6.32-131.21.1.el6.x86_64 #1 SMP Tue Nov 22 14:15:09 CST 2011 x86_64 x86_64 x86_64 GNU/Linux My present ulimit settings are as follows : $ ulimit -a core file size (blocks, -c) unlimited data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) unlimited max locked memory (kbytes, -l) unlimited max memory size (kbytes, -m) unlimited open files (-n) 999999 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) unlimited real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) unlimited virtual memory (kbytes, -v) unlimited file locks (-x) unlimited However when I start freeswitch "bin/freeswitch -nc -nonat -nonatmap", I get the following : Error: stacksize 8192 is too large: run ulimit -s 240 from your shell before starting the application. auto-adjusting stack size for optimal performance... Surely this is incorrect, because I am running a 64 bit kernel, 240 is the recommended value for 32 bit ?