This is way beyond my understanding of Asterisk but it appears that an IE is an information element (username etc) and of course IAX is Inter-Asterisk eXchange, the Asterisk and Allstar linking protocol. 

Outside of the obvious reboot I don’t know how one would clear what appears to be the iax_ie buffer. I remember we found a bug where when a large number of nodes (say 100 or more) were connected app_rpt would crash. Jim fixed it by making some buffer larger. Perhaps that’s what your diff shows. 

I’ve been complaining to Jim about short uptimes so he build a compile for me with a command “memory show summary”.  I set up a cron to log that every hour. Just before the last crash iax2-parser exploded in size. So I’m sure there is still a bug to be squashed. We’re exploring the squashing options at this time.