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IBM SDK, Java Technology Edition, Version 6: Current news



Support information for IBM® SDK, Java™ Technology Edition, Version 6 that is not available in the user documentation.


The information to support IBM SDK, Java Technology Edition, Version 6 is available in the product documentation.

Note: Support for IBM SDK, Java™ Technology Edition, Version 6 (J9 VM2.6) has ended for some platforms unless covered by an extended support contract or embedded in an IBM product that has not reached its own end of service date. End of service dates for the IBM SDK are shown in the JavaSDK developer center. End of service dates for all IBM software products are listed here.

InstallAnywhere installation packages

There are two types of InstallAnywhere package:

Installing these packages also configures your system, for example by setting environment variables. You must use a user account with ROOT authority to install this type of package.
Installing these packages extracts the files to your system, but does not perform any configuration. This type of package does not require ROOT authority to complete the installation.

More information on large page requirements for Linux

This information is supplementary to the Configuring large page memory allocation topic in the IBM Knowledge Center.

The JVM depends on the SYSV shared memory system calls shmget and shmat. If a request to allocate a large page failed, ensure that the values of the kernel parameters SHMMAX and SHMALL are sufficient for your operating system to allocate large pages.

SHMMAX: The maximum size of a shared memory segment, in bytes.
SHMALL: The total amount of shared memory in the system, in either bytes or pages.

Supplementary information is available for the following updates to this release:

To compare the IBM SDK functionality with Oracle build levels at each service refresh level, see Comparative Oracle build levels.

For information about security fixes, see Security Alerts.
For a list of the IBM fixes included, see IBM SDK, Java Technology Edition, Version 6 fixes.
To download the last service refresh, see IBM developer kits.

For information about the daylight saving time changes included in service refreshes and fix pack levels, see Olson time zone updates. Later updates can by applied using the IBM Time Zone Update Utility for Java (JTZU).

Service refresh 16, fix pack 60

Out of memory exceptions when running applications with compressed references enabled

The Oracle CPU for January contains an update for CVE-2018-2582 to fix vulnerabilities in the Hotspot virtual machine (VM) that might be exploited by Java web start applications and applets. Fixes are also applied for the OpenJ9 virtual machine. The fix increases the amount of low memory used for VMs that use compressed references. Customers who are running close to the maximum amount of allowed 32-bit memory might experience out of memory exceptions. A possible workaround is to use the -Xmcrs option to secure space in the lowest 4GB memory area for any native classes, monitors, and threads that are used by compressed references.

For more information about this option, see -Xcmrs.

Security checking

To improve security, the security checks in the following APIs are now enabled by default, when the SecurityManger is enabled:

  •, String[])
  •<any parameters>)

You can disable security checking for these APIs by setting the following system properties on the command line:

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Service refresh 16, fix pack 30

The URL for version 1.8 of the certified JCE FIPS guide on the Computer Security Resource Center website (mentioned in IBM Knowledge Center) is now available:

Service refresh 13, fix pack 2

This fix pack includes a change to the default value for the RMI property java.rmi.server.useCodebaseOnly from false to true, which might cause unexpected errors for applications that use RMI. For more information, see

On Windows, improvements are made to the way that Runtime.exec decodes command strings. However, applications specifying commands that contain spaces in the program name, or that use quotation marks incorrectly, might fail to start. For more information, including guidance on resolving problems, see

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Service refresh 13, fix pack 1

This fix pack contains a security fix for the Oracle security vulnerability, CVE-2013-0169. For any further security fixes in this release, see Security alerts.

A security enhancement is included to correctly validate certificates on jar files of applications. After upgrading, a CertificateException occurs for any applications in one of the following scenarios:

  • The application jar is not properly signed.
  • The application jar has incorrect certificates.
  • A certificate in the certificate chain is revoked.

To avoid these exceptions, make sure that your application jars are signed with valid certificates before upgrading from an earlier release. This issue relates to APAR IV38456.

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Service refresh 13

Non-blocking registration of interested operations with selectors on the AIX operating system

In this release, the implementation of the registration of interested operations with the java.nio.channels.Selector class has been modified to avoid blocked threads.

In previous releases, this implementation could cause blocking of threads on the AIX® operating system. If a Java application used the java.nio.channels.SelectionKey.interestOps() method to register an interested operation with a Selector object that was engaged in a polling operation, the registering thread could be blocked. A thread that is blocked in this way can cause the application to hang or timeout. The following Java stack traces from such a situation show that the first thread is performing a poll operation, and the second thread is blocked:

3XMTHREADINFO      "Thread-2" TID:0x31E65800, j9thread_t:0x31C9764C, state:R, prio=5
3XMTHREADINFO1            (native thread ID:0x2AA00A5, native priority:0x5, native policy:UNKNOWN)
4XESTACKTRACE          at sun/nio/ch/PollArrayWrapper.poll0(Native Method)
4XESTACKTRACE          at sun/nio/ch/PollArrayWrapper.poll(
4XESTACKTRACE          at sun/nio/ch/PollSelectorImpl.doSelect(
4XESTACKTRACE          at sun/nio/ch/SelectorImpl.lockAndDoSelect(
4XESTACKTRACE          at sun/nio/ch/
4XESTACKTRACE          at sun/nio/ch/
4XESTACKTRACE          at
4XESTACKTRACE          at java/lang/

3XMTHREADINFO      "main" TID:0x30A65500, j9thread_t:0x301162D4, state:B, prio=5
3XMTHREADINFO1            (native thread ID:0x14A005F, native priority:0x5, native policy:UNKNOWN)
4XESTACKTRACE          at sun/nio/ch/SelectionKeyImpl.nioInterestOps(
4XESTACKTRACE          at sun/nio/ch/SelectionKeyImpl.interestOps(
4XESTACKTRACE          at BlockIntOpsReg.main(

This thread blocking was caused by the pollset implementation using a Java cache of limited size to store requests for registration of interested operations. When the cache reached its size limit, the implementation attempted to register all the requests in the Java cache into the native AIX pollset cache, which could result in blocked threads. From this release, the Java cache size is unlimited, and interested operations are registered just before the next poll operation, to avoid blocking of threads.

For more information about I/O polling on the AIX operating system, see the following developerWorks article: Efficient I/O event polling through the pollset interface on AIX.

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Service refresh 12

PKCS11 security provider

A new library is available that allows the IBMPKCS11Impl provider to run on the Linux AMD64 platform.

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Service refresh 10, fix pack 1

The following Oracle change is included with IBM SDK for Java version 6 service refresh 10, fix pack 1:

KeyboardFocusManager implementation

This change relates to Oracle security vulnerability CVE-2012-0502.
The KeyboardFocusManager specification explicitly allows a single, global KeyboardFocusManager for all applets. Some public methods are unsafe for such implementations.
As a result of the fix, the following methods now throw a java.lang.SecurityException if they are invoked on a java.awt.KeyboardFocusManager that is not the current java.awt.KeyboardFocusManager for the calling thread's context:

  • java.awt.KeyboardFocusManager.setGlobalFocusOwner(Component focusOwner)
  • java.awt.KeyboardFocusManager.clearGlobalFocusOwner()
  • java.awt.KeyboardFocusManager.setGlobalPermanentFocusOwner(Component PermanentFocusOwner)
  • java.awt.KeyboardFocusManager.setGlobalFocusedWindow(Window focusedWindow)
  • java.awt.KeyboardFocusManager.setGlobalActiveWindow(Window activeWindow)
  • java.awt.KeyboardFocusManager.setGlobalCurrentFocusCycleRoot(Container newFocusCycleRoot)

Tuning options for the Generational Concurrent (gencon) Garbage Collection policy

The -Xgc option can be used with a number of parameters to fine-tune garbage collection. The following options apply to the gencon policy:

This option turns off the adaptive tenure age in the generational concurrent GC policy. The initial age that is set is maintained throughout the run time of the Java™ virtual machine. See scvTenureAge.
This option sets the initial scavenger tenure age in the generational concurrent GC policy. The range is 1 - 14 and the default value is 10.

For more information about tenure age and the -Xgc option in the product documentation.

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Comparative Oracle build levels

The following table indicates the Oracle FCS build level that has comparative functionality to recent releases of the IBM SDK:

IBM SDK 6 Oracle Java 6 FCS build
GA Update 04 Build 04
Service Refresh 1 Update 05 Build 13
Service Refresh 2 Update 07 Build 02
Service Refresh 3 Update 07 Build 02
Service Refresh 4 Update 07 Build 02
Service Refresh 5 Update 10 Build 33
Service Refresh 6 Update 14 Build 07
Service Refresh 7 Update 17 Build 02
Service Refresh 8 Update 18 Build 07
Service Refresh 9 Update 21 Build 06
Service Refresh 10 Update 27 Build 05
Service Refresh 11 Update 32 Build 05
Service Refresh 12 Update 32 Build 05
Service Refresh 13 Update 39 Build 02
Service Refresh 14 Update 51 Build 09
Service Refresh 15 Update 65 Build 11
Service Refresh 16 Update 75 Build 13
Service Refresh 16 Fix Pack 1 Update 81 Build 08
Service Refresh 16 Fix Pack 2 Update 85 Build 13
Service Refresh 16 Fix Pack 3 Update 91 Build 13
Service Refresh 16 Fix Pack 4 Update 95 Build 11
Service Refresh 16 Fix Pack 7 Update 101 Build 14
Service Refresh 16 Fix Pack 15 Update 105 Build 15
Service Refresh 16 Fix Pack 20 Update 111 Build 12
Service Refresh 16 Fix Pack 25 Update 115 Build 12
Service Refresh 16 Fix Pack 30 Update 121 Build 09
Service Refresh 16 Fix Pack 35 Update 131 Build 14
Service Refresh 16 Fix Pack 41 Update 141 Build 12
Service Refresh 16 Fix Pack 45 Update 151 Build 10
Service Refresh 16 Fix Pack 50 Update 161 Build 13
Service Refresh 16 Fix Pack 60 Update 181 Build 10

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Document information

More support for: Runtimes for Java Technology
Java SDK

Software version: 6.0

Operating system(s): AIX, HP-UX, Linux, Solaris, Windows, z/OS

Software edition: Java SE

Reference #: 1587401

Modified date: 20 July 2015

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