IBM SDK

As with Java™ SDKs for other IBM® platforms, z/OS® Java SDK licensed programs are supplied for industry standard APIs. The z/OS SDK products are independent of each other and can be ordered and serviced separately.

At the time of writing, the following Java SDKs are available for z/OS:

The Java SDK 1.3.1 product called IBM Developer Kit for OS/390®, Java 2 Technology Edition works on z/OS as well as the older OS/390. This is a 31-bit product. Many z/OS customers have moved (or migrated) their Java applications to the latest versions of Java.
IBM SDK for z/OS, Java 2 Technology Edition, Version 1.4 is IBM's 31-bit port of the Sun Microsystems Java Software Development Kit SDK) to the z/OS platform and is certified as a fully compliant Java product. IBM has successfully executed the Java Certification Kit (JCK) 1.4 provided by Sun Microsystems, Inc.
IBM SDK for z/OS, Java 2 Technology Edition, Version 1.4 runs on z/OS Version 1 Release 4 or later, or z/OS.e Version 1 Release 4 or later. It provides a Java execution environment equivalent to that available on any other server platform.
IBM 64-bit SDK for z/OS, Java 2 Technology Edition, Version 1.4 allows Java applications to execute in a 64-bit environment. It runs on z/OS Version 1 Release 6 or later. As with the 31-bit product, this product allows usage of the Java SDK1.4 APIs.

IBM provides more information about its Java SDK products for z/OS on the Web at:

http://www.ibm.com/servers/eserver/zseries/software/java/