Archive-file-lists

ARCHandler  keeps  a certain amount of unused archive-file-lists (a list of
all the files and directories in an archive) in memory ( BUFFERS). This has
the  advantage  that the handler won't have to re-list the archive on every
access. This results in a faster response.
This also has a small side-effect, the handler keeps a lock on all archives
whose  archive-file-list  is still in memory. The handler uses a simple LRU
(least-recently-used) replacement rule to select the archive-file-list that
will be freed when another archive-file-list is no longer used. As a result
the  archive-file-list-lock  won't  be released until enough other archives
are used.

If,  at  a  certain  moment,  you want to free all unused archive-lists and
locks you can use the  FlushARC command.