You may have problems with web servers writing logs with big sizes so archiving them may be a solution, you may use a .vbs file, a vb script, and run it daily as a scheduled job on the server.
If you only need a solution, and do not know much vb script, you can find more info at the following link http://www.808.dk/?code-iis-log-housekeeping
Using an archiver as 7 zip that it’s free, may help, note that the scripts using compression need the command line version of the free 7-Zip compressor available on http://www.7-zip.org/download.html