PostgreSQL and PHP for a web site, yes but ...

How do I set up (here, to extend it) the maximum number of clients for a
database ?
I start postmaster with 'postmaster -i -N 16' (I can't use more than 16
due to the IPC sys V blabla ...).
I know N is the number of backend server processes, but does it have a
result on the maximum number of clients ?
Here's the problem i have on the web site i'm currently developping:
Unable to connect to PostgreSQL server: "Sorry, too many clients already
in -file i'm using to open the connection-" (i only open the connectiion
if there isn't one already opened) ...
Here's the stuff from php.ini:
[PostgresSQL]
pgsql.allow_persistent = On ; allow or prevent persistent link
pgsql.max_persistent = -1 ; maximum number of persistent links. -1 means
no limit
pgsql.max_links   = -1 ; maximum number of links (persistent+non
persistent).  -1 means no limit

So, it looks like the problem isn't coming from PHP ...
I'm worrying a bit because PostgreSQL is supposed to be a good choice
for dynamic web sites, but eh ... will i be able to have more than a
handful of visitors at the same time ? :)