9.5.0-P2 and socket: too many open file descriptors

[Fr34k]

Hello,
Running 9.5.0-P2 on Solaris 9 and I continue to get "socket: too many open file 
descriptors" messages.
I have tried "ulimit -n foobar" where foobar has been various numerical values 
and I still get the error.
Am I just not assigning a large enough foobar?
Do I have to recompile bind after such an adjustment?
Should I tweak something else?
TIA