[Xymon] How to increase max message size

I have a few hosts that are sending large status messages and am getting:

2011-12-11 20:16:24 Oversize status msg from 64.94.253.22 for host.company.com:ports truncated (n=340208, limit=262144)

I've tried increasing MAXLINE in xymonserver.cfg, but that does not seem to have fixed the issue. Where can I increase this, as I'm sick of seeing xymond being yellow all the time.

Thanks! Skadz