Stash crash after some hours on OS X server

After some time, without important load, Stash crash with Too many open files errors in catalina.out (you can download a complete version of the log file here: http://extranet.ttree.ch/~dfeyer/catalina.out.gz)

Stash run on OSX 10.6 / JAVA 6

1. uname -a
   Darwin everest.intranet.ttree.ch 10.8.0 Darwin Kernel Version 10.8.0: Tue Jun 7 16:33:36 PDT 2011; root:xnu-1504.15.3~1/RELEASE_I386 i386

I try to increase the ulimit values, but without any success, stash continue to crash:

1. ulimit -a
   -t: cpu time (seconds) unlimited
   -f: file size (blocks) unlimited
   -d: data seg size (kbytes) unlimited
   -s: stack size (kbytes) 8192
   -c: core file size (blocks) 0
   -v: address space (kb) unlimited
   -l: locked-in-memory size (kb) unlimited
   -u: processes 2000
   -n: file descriptors 32768

Does Stash need more thant 32768 open files ? We dont host more than 40 repository. Some projects are big, but mainly average size project. We have a bit less than 3 Go of data in our Stash home directory.

Thanks for your help