Configure Squid so that it doesn't create any log files, except for the swap.state file(s).
Write a simple Perl or awk script to calculate your cache hit ratio from access.log .
How does an "access denied " response appear in the access.log ?
Does store.log have the same number of, more, or fewer, entries than access.log ?
Take a file number from store.log and find the corresponding file in the disk cache. Examine the file and make sure you've found the correct response.
Develop and implement a policy for archiving old cache log files. Consider where and how they will be stored, for how long, and who has permission to access them.