Fluentd: How to rotate td-agents/fluentd's own logs and .gz files?

Question

td-agent also creates logs. e.g. "td-agent.log" file. besides that it also creates .gz files. I want to rotate the .gz files. currently there are more than a dozen of these .gz files in /var/log/td-agent directory.

I tried following in td-agent config:

<system>
  <log>
    rotate_age 5
    rotate_size 1000
  </log>
</system>

but this does not rotate .gz files. I use td-agent v4. Any help would be appreciated!