[syslog-ng]directory

hallo all a quick (and perhaps for most, annoying) question, which i was unable to find an answer to anywhere: Im logging to a loghost from many clients and need to know how to limit the size of logs created on the loghost. Can this be done per directory or perhaps by facility ? If so then how ? I saw this option: log_msg_size however im not sure if this refers to the size of one single message sent or if this refers to an actual log file or directory. thankyou AlanCB