MonetDB and cpu resources management

Hi, I'm trying to set the maximum number of cores using gdk_nr_threads parameter but it doesn't seem to work for me. I've tried "variants" of this command: monetdbd set gdk_nr_threads=4 start /my/dbfarm but it seems like gdk_nr_threads is not a supported property. Additionally to this, I would like to ask how does MonetDB handle concurrent user sessions and the available cpu resources ? The manual says there is support for "inter- and intra- parallelism". Can someone roughly explain me what to expect or give me a pointer to the code that is responsible for resource management ? Cheers! Dimitris