Hi,
 
I'd just like to say that I found the answer to my own question in the documentation:
 
With 3.x versions, you have to load ctl and cfg_rpc modules and execute:
 
sercmd cfg.set_now_int core mem_dump_pkg <pid>
 
http://www.kamailio.org/dokuwiki/doku.php/troubleshooting:memory
 
I did also write a patch to suppress the full memory dump, because I am only interested in the first lines of the status (total usage). This way I the server doesn't get blocked - full memory dump usually takes a VERY long time. Patch is attached and I'd be glad if something similar would be integrated in the trunk.
I've introduced a mem_summary option "16" to control that behavior.
 
Best regards,
Ricardo.