Setting specific JRE to Tomcat 7
#see http://www.codejava.net/servers/tomcat/4-ways-to-change-jre-for-tomcat
2. Changing JRE by using “setenv” script
We can change the JRE for Tomcat by setting the JRE_HOME variable in a script file called setenv.bat (on Windows) or setenv.sh (on *nix). This file does not exist by default, so create such file and place it under CATALINA_BASE\bin directory (CATALINA_BASE is the Tomcat installation directory).
On *nix, create the setenv.sh file with the following content:
JRE_HOME=/usr/java/jdk1.7.0_03/jre
CATALINA_PID="$CATALINA_BASE/tomcat.pid"