Beginning with SuSE 12 distros (including SLES12), SuSE has implemented systemd.
systemd is (disputably) meant to eventually replace SysV init scripts on Linux.
SuSE 12 distros continue to support both SysV init scripts, as well as the new systemd.
However, it is likely that your desire to automatically start Tomcat on each system boot has already been anticipated by SuSE; which already has a systemd entry in SuSE 12 distros.
Hence, on SuSE 12 distros, Tomcat automatic start can be enabled in:
YaST->System->Services(Manager)->Tomcat
Click the Enable/Disable button to enable or disable automatic startup.
Also, you might find the following command-line item of value:
systemctl status tomcat
systemctl start tomcat
systemctl stop tomcat
(More commands can be found in man systemctl.)