Increase cache size

[Lumir ml.]

        hello,

        I increased cache size in my config file from this line

        cache_dir /usr/local/squid/cache 400 16 256
to this
        cache_dir /usr/local/squid/cache 800 16 256

        I apllied quota tu user under which is squid running and for last 10 days 
I watched disk space used - but squid still uses only 400 MB as before 
change. Squid was comletely restarted. What I can do with it?

                thanks

                        Lumir