[libvirt-users] Problem in getting memory statistics

Hello, I need to get how much memory is used by a guest system, in order to implement some monitoring function which tells me if the system is overstressed. I am currently using java apis and the binding which was suggested to me was Domain.memoryStats(); This is a binding to int virDomainMemoryStats (virDomainPtr<http://libvirt.org/html/libvirt-libvirt.html#virDomainPtr..., virDomainMemoryStatPtr<http://libvirt.org/html/libvirt-libvirt.html#vi..., unsigned int nr_stats, unsigned int flags). Problem is that it returns me just tags 0,6 and 7. Looking at the documentation I see they are not what I am looking for...I would rather need 4 (VIR_DOMAIN_MEMORY_STAT_UNUSED) and 5 (VIR_DOMAIN_MEMORY_STAT_AVAILABLE). Is there a way to set them?