CACHEFILE parameter ==  CACHEFILE=fileNameSpec
                    --  default: CACHEFILE='$[server:%P/%L/%p]'

CACHEFILE specifies how the file name of a cache file is formed. The name is derived mainly from informations about server host and requested URL. Those informations are specified in the format "$[server:format]" where the format is a sequence of symbols each refers a part of an URL scheme://host.d2.d1:port/path as follows:

%P	--	scheme	Protocol name part
%L	--	host.d2.d1:port	Login (or site) part
%H	--	host.d2.d1	Host name
%T	--	port	Port number
%h	--	d1/d2/host	hierarchical host name directory
%d	--	d1/d2	hierarchical domain name directory
%1	--	d1	top level domain
%2	--	d2	second level domain
%p	--	path	URL-path part
%Q	--	host.d2.d1.d0	use FQDN of a host name (like %Q%L or %Q%H)

Another formatting pattern is "$[hash:format]" which hashes a string generated by format into hexadecimal value ranging from "00" to "1f". This will be useful to divide a single huge directory containing all servers into 32 small directories, which can be on physically different disks.
Example:

CACHEFILE='$[server:%P]/$[hash:%H]/$[server:%L/%p]'