Delaying POST requests until they are there?

I'm running squid in accelerator mode.

From the timings I'm doing on the backend apache, I get the impression
that squid passes over a request as soon as it arrives and feeds the
data coming from a POST request at about the same transmission rate as
they come in.

My questions are:

- Is this the way it works?

- Can squid be tweaked to wait until all POST data have arrived and
  then pass the request to the backend server?

-- 
andreas