Mod-perl handling of Chunked POST's

I am using Plack::Handler::Apache2 to dispatch to a custom psgi which 
handles POST requests of large files.  I currently have the client side of 
this chain posting with pl_upload API (not that it matters) which allows 
the post to be sent chunked.

Empirically this appears to only invoke my psgi with a single 'chunk size' 
upload, which suggests to me that delegation to the handler is not 
deffered until all chunks have been consumed.

I'm just wondering whether anyone can point me in the appropriate 
direction wrt figuring out how chunked posts should be handled in this 
scenario.  Particularly whether it is up to the handler to re-assemble the 
payload or not; I'm pretty sure this isn't the case?

I'd be grateful if someone would point me in the right direction?

Cheers,

Raf