Starting Cloudstack-specific Tomcat engine cloudstack-management [fail]

[5??????]

hi!
i got a new ubuntuserver 12.04 i386 to install Cloudstack-management version 
4.2,i followed the guide on cloudstack.org step by step, but the tomcat just 
can't run.
i checked the log in /var/log/cloudstack/management,there is only a 
setupManagement.log and seems nothing useful.then i went through the 
/var/log/syslog,found pages of error like "ubuntuServer1 jsvc.exec[3612]: Error 
occurred during initialization of VM#012Could not reserve enough space for 
object heap".what might be the problem?
thank you!