The Rebex.FileLogWriter class does not impose any file size limit. It simply writes log entries to the file specified during its construction. Any size/date rolling capabilities has to be implemented manually.
However, I am little confused now. Are you asking about logging using the Rebex.FileLogWriter class (a .NET API), or about logging in Rebex TLS Proxy (a standalone app)?
If you are asking about logging capabilities in the Rebex TLS Proxy, the settings are not configurable. Currently:
Max file size = 1GB. (size per single file, if exceeded another file is created)
File retention = 31 files.