Thanks Jochem for your reply.

The solution you described is the only one I found acceptable.

1] there is no way to destroy link to database created by ibase_pconnect()
2] there is no way to restart apache or firebird (from my position)

I already have a switch which switches between functions connect() or
pconnect() in my webapplication. And I already know that persistent link
to database dies in about 20 minutes on one server where the applicaion
runs.

As you may expect, when somebody needs something, he needs it
immediately, not after 20 minutes or one hour ;-)

I just wanted to know, if somebody has solved this problem different
way. Or faster ;-)

Thank you
Michal