WHM lets you specify what Apache logs get into a rotation for use and archiving based on their size. You can specify exactly which logs are in this rotation from the cPanel Log Rotation Configuration module within the Services Configuration category.
To enter a log file into the rotation for usage and archiving, check the checkbox next to the file name and click Save.
Similarly, to remove a log file from the rotation, uncheck the checkbox next to the file name and click Save.
You can also change the specified size a log file needs to reach for it to trigger a rotation in the Log Rotation Size Threshold configuration linked in the description at the top of this page. The default threshold is 300MB.