JKS stands for JavaKeyStore. You have a java tool named keytool (under jdk bin directory) which lets you to manage the certificates. If you search the web for java keystore tutorials you will find good links. If you are willing to spend some money on books then try Java Security from Orielly publications.
You can search on javaworld.com or onjava.com site. [ August 31, 2006: Message edited by: Purushothaman Thambu ]