xlib error

Hello!
Im running tight VNC on Red Hat Enterprise Linux 4.0.
How can I increase the number of X clients that I can run
in a VNC session?I need to run aproximately 500 programs in one VNC session,
but at this time I can only 236 -> i've tryed to launch 250 xclock's in background
and when it comes to 237, the error Xlib:Maximum number of clients reached
comes out. Please, help me on solving that issue!

I have not messed with vnc for years. There is a ~/.vncrc file and /etc/vnc.conf file as well. Those control user-level and system level settings. I do not recall a concurrent client limit setting. Check your docset.

My real question is - are you really sure you need 500?

my objective is to solve this issue and find out why I can launch only 237 programs and where this clients number could be changed, I don't have such files in such directories which you posted. I have .vnc/xstartup file with parameters:
#!/bin/sh

# Uncomment the following two lines for normal desktop:
unset SESSION_MANAGER
exec /etc/X11/xinit/xinitrc

[ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
[ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
xsetroot -solid grey
vncconfig -iconic &
xterm -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
startx&

any idea?