> Hi, I'm not sure if I'm looking in the right place, but does the
> kernel parameter MAXUSERS (currently set to 64) have any effect of
> how many entries (currently 63, with about 115 users actually logged in)
> can be stored in utmp?
yes. this parameter only sets few others (open files, processes)
from this.

> When defining MAXUSERS > 64 config will complain, and I realise that
> in param.c that parameter is used with maxfiles.
>
> Could this be dynamically tuned with sysctl?

yes