java 7: should users be aware of changes in heap memory handling?

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http://serverfault.com – After installing the latest Java 7 Development Kit (Java SE 7u11) on my Windows 7 Professional 32bit PC with 4Gb RAM, I noticed I can't allocate much memory for Tomcat. Whereas these memory settings worked for Java Development Kit 6u38: set JAVA_OPTS=-server -Xms978m -Xmx978m -XX:MaxPermSize=512m ...when run with jdk7, these settings cause the Tomcat launcher to exit with following error message: Error occurred during initialization of VM Could not reserve enough space for object heap Error: Could not create the Java Virtual Machine. Error: A fatal exception has occurred (HowTos)