How do I tune cacheing (sic) options?

I have a jabber installation that is running awesome but my log files keep filling up due to constantly repeated messages:

=WARNING REPORT==== 2013-11-22 22:15:54 ===
W(<0.346.0>:cache_tab:473) : shrinking table:
** Table: shared_roster_ldap_user
** Processes Number: 4
** Max Size: 250 items
** Shrink Size: 125 items
** Life Time: 300000000 microseconds
** Hits/Miss: 0/10626
** Owner: <0.343.0>
** Cache Missed: true
** Instruction: you have to tune cacheing options if this message repeats too frequently

Problem is I have NO IDEA how to follow the Instruction above...

I have googled pretty much every word in the message above but come up empty...How do I do the Mnesia tuning this is referring to? I'm happy to read how to do it but I can't find any documentation anywhere.

Thanks!
Steve