UFS2 limits

[no-spam at people.net.au]

Hi,
I have a FreeBSD server that has about 10,500 subdirectories within a single
directory.
This number will keep rising and I assume UFS2 has a limit to the number of
sub-directories in a single directory - can anyone tell me what it is?

What about ZFS?

At some point I'll have to re-arrange things so that I have a deeper directory
structure, just wondering when I'll hit the limit so I can plan in advance :-)

Cheers,
Ian