what happens if you set the value of maxCacheFileNumber to 0 ?
EXPIRATION defines, when the cached entries should be deleted in cache dir.
if I remember right you cannot disable reports cache at all because some destinations (printer, etc.) will not work without it.
So I realize that the title of my post is not correct.
What we want is to delete the file immediately after it was created and processed.
To get the desired behaviour I would like to set both parameters EXPIRATION and TOLEERANCE to 0.