Negotiated private cache storage allocation

Hi,

Is anyone aware of any proposals that extend HTTP to allow servers and
clients to negotiate client-side storage allocation for client-side
(private) caches?

Basically, I'm looking for a way for a server to indicate how much
storage should be allocated for caching responses from a particular
domain name, and possibly also for the client to be able to indicate
how much allocation was actually possible.

Aside from that, if you have any thoughts on whether or not this is
really feasible or is just a plain bad idea - please let me know

Thanks,
Mike