In PCo 15.0 and later, the logs are stored in the Microsoft Event Log structure, and as such can be configured for a max size as well as being self-purging after a certain size. You can find the name of the Event Log at the bottom of the Agent Instance Logs Tab page, and then use the Microsoft Event Viewer applet to access the log properties and adjust as required.
Best practices for setting log levels for Production is at Warning. Lower levels such as Verbose and Information are used for troubleshooting and/or validation during design and testing.
Regards, Steve