Teraspace storage model native methods for Java

The iSeries™ Java™ virtual machine (JVM) now supports the use of teraspace storage model native methods. The teraspace storage model provides a large process-local address environment for ILE programs. Using teraspace allows you to port native method code from other operating systems to i5/OS™ with little or no source code changes.

For details about programming with the teraspace storage model, see the following information:

Chapter 4 of ILE Concepts

Chapter 17 of WebSphere^® Development Studio ILE C/C++ Programmer's Guide

The concept for Java native methods created for the teraspace storage model is very similar to that of native methods that use single-level storage. The JVM passes the teraspace native methods a pointer to the Java Native Interface (JNI) environment that the methods can use to call JNI functions.

For teraspace storage model native methods, the JVM provides JNI function implementations that utilize teraspace storage model and 8-byte pointers.

Creating teraspace native methods

To successfully create a teraspace storage model native method, your teraspace module creation command needs to use the following options:

     TERASPACE(*YES) STGMDL(*TERASPACE) DTAMDL(*LLP64)

The following option (*TSIFC), to use teraspace storage functions, is optional:

     TERASPACE(*YES *TSIFC)

Note: If you do not use DTAMDL(*LLP64) when using teraspace storage model Java native methods, calling a native method throws a runtime exception.

Creating teraspace service programs that use native methods

In order to create a teraspace storage model service program, use the following option on the Create Service Program (CRTSRVPGM) control language (CL) command:

     CRTSRVPGM STGMDL(*TERASPACE)

In addition, you should use the ACTGRP(*CALLER) option, which allows the JVM to activate all teraspace storage model native method service programs into the same teraspace activation group. Using a teraspace activation group this way can be important for native methods to efficiently handle exceptions.

For additional details on program activation and activation groups, see the following information:

Chapter 3 of ILE Concepts

Using Java Invocation APIs with teraspace native methods

Use the Invocation API GetEnv function when the JNI environment pointer does not match the storage model of the service program. The Invocation API GetEnv function always returns the correct JNI environment pointer. For more information, see the following pages:

Java Invocation API

JNI Enhancements

The JVM supports both single-level and teraspace storage model native methods, but the two storage models use different JNI environments. Because the two storage models use different JNI environments, do not pass the JNI environment pointer as a parameter between native methods in the two storage models.