Miscellaneous system property command-line options

Use the system property command-line options to set up your system.

-D<name>=<value>: Sets a system property.

Many system properties are associated with components of the SDK. Information about these system properties can be found at the following links:

Other system properties are listed here:

-Dcom.ibm.dbgmalloc=true

This option provides memory allocation diagnostic information for class library native code.

When an application is started with this option, a Java™ dump records the amount of memory allocated by the class library components. You can use this option together with the -Xcheck:memory option to obtain information about class library call sites and their allocation sizes. Enabling this option has an impact on throughput performance. For sample Java dump output, see NATIVEMEMINFO.

-Dcom.ibm.rational.mvfs.checking=[true|false] (Windows only)

Use this property to improve the performance of Multi Version File System (MVFS) file systems.

The WinNTFilesystem methods getModifiedTime and getBooleanAttributes use the windows methods API_wstati64() and _wfindfirsti64() instead of the defaults. This property is not enabled by default because it can cause performance degradation on local file systems. The property also causes degradation on remote Windows shares where there is no Windows directory cache for the remote file system.

-Dcom.ibm.signalhandling.ignoreLogoff=[true|false] (Windows only)

Start of changes for service refresh 6 fix pack 10 This property does not apply from service refresh 6, fix pack 10. End of changes for service refresh 6 fix pack 10

Windows issues a CTRL_LOGOFF_EVENT when a user logs out of an interactive Windows service. By default, the JVM ends when this signal is received. Setting this property to true (the default is false) prevents the JVM ending when a CTRL_LOGOFF_EVENT signal is received. Start of changes for service refresh 6 fix pack 10 From service refresh 6, fix pack 10, this property no longer has any effect. To achieve the same result, you can use the -Xrs command-line option to disable the handling of hardware exceptions by the VM. However, you should use the -Xrs option with care because it affects more than just the CTRL_LOGOFF_EVENT signal. For more information, see -Xrs. End of changes for service refresh 6 fix pack 10

-Dibm.awt.mediumColor=true (AIX® only)

From IBM® SDK, Java Technology Edition, Version 8, the default SystemColor settings of Abstract Windows Toolkit (AWT) components are changed. To revert to the original color palette settings, set this property on the command line.

This property is not enabled by default.

-Dibm.swapLF=true (z/OS® only)

By default, the \u000A Unicode new line character is mapped to the 0x15 EBCDIC character. Set this property to true to map the \u000A character to the 0x25 EBCDIC character instead. This behavior might be useful if you have a z/OS system that interacts with a system that uses a different operating system. For more information about the historical background to new line characters in EBCDIC format, see Unicode Newline Guidelines.

Note: If you use this option, also convert all configuration files to ASCII format because the new line character (\n) is not recognized if the files are in EBCDIC format.

Start of changes for service refresh 6 fix pack 25

-Dibm.swapLF=disable can be used if you do not want to enable the swapLF functionality. The disable option is different from setting the value of the ibm.swapLF property to false, or to not setting it explicitly, in which cases it is possible to change the property value to true programmatically as shown in the following example.

System.setProperty("ibm.swapLF", "true");

Use of the disable option may deliver better performance by reducing the overhead of System.getProperty calls within the SwapLF support. End of changes for service refresh 6 fix pack 25

End of changes for service refresh 6 fix pack 25

-Dsun.rmi.transport.tcp.connectionPool=val

Enables thread pooling for the RMI ConnectionHandlers in the TCP transport layer implementation.

val is either true or a value that is not null.