HOW TO CHANGE FROM 32 bit JAVA TO 64 bit JAVA VERSION:

*** Get the newest version of JDK and JRE which support 64 bit
1) #rm /usr/bin/java
2) # ln -s /usr/jdk/jdk 1.5.xxx/bin/sparcv9/java /usr/bin/java

For Tomcat profile enable 64 bit:
JAVA-OPTS="-server -Xmx4096m -d64"

You can refer here for detail if installing JDK 32 bit and 64 bit:
http://java.sun.com/j2se/1.5.0/install-solaris-64.html