Everything that I know about this parameter I've already quoted in an earlier comment, from the paragraph in the Nocedal and Wright book.  It is possible that the default strategy for setting this parameter is bad under certain conditions, but it is the only strategy that I could find in the Nocedal and Wright book.  If you want, you could remove it from the arg list, and perhaps add some kind of note into the source code to the effect that it is possible that there are better strategies for setting this parameter.  But I don't have any other example of such a strategy.