HPUX 11 + Oracle 8.1.6.2 = not enough space

Hello,

I have a problem.

Platform: HP, OS: HPUX 11.00
Oracle: 8.1.6.2.0 Enterprise (8.1.6.0.0 is also affected)

I have installed and created three instances successfully; everything is fine until some amount of processes in OS is reached. This number is about 270-280 in operating system. If I try to connect to any database (of three) I get a ORA-12500 error. But the most common is the 'not enough space' error. For example:

/usr/lib/dld.sl: No Error
/usr/lib/dld.sl: Not enough space

or

ksh: cannot fork: no swap space

or

The fork function failed. There is not enough memory available.

At this moment I cannot execute any command (ps, ls, vi and so on) until I kill some sessions.
I am not running out of resources, there is plenty of free RAM memory, swap is used in about 25%, CPU load is very low.

For example:
root)/:# swapinfo

             Kb      Kb      Kb   PCT  START/      Kb
TYPE      AVAIL    USED    FREE  USED   LIMIT RESERVE  PRI  NAME
dev     1048576  140256  908320   13%       0       -    1  /dev/vg00/lvol2
reserve       -  906008 -906008

Please, help

Regards,

--
Andrew Rajczakowski