Java SDK options and system properties

Java™ options and system properties are configured in the batch launcher by using the OPENJ9_JAVA_OPTIONS environment variable. These options can include most of the options that are usable with the standard java command-line launcher, including -X and -D options.

This table includes options that are commonly used with the batch launcher. For a full list, use the java -help or java -X commands. For more information about the options, see Eclipse OpenJ9 command-line options.

Table 1.
Option	Description
`-verbose:class`	This option prints class loader activity to the `//SYSOUT` data set, which is helpful for resolving `ClassNotFound` errors.
`-D<name>=<value>`	Used to set any Java system property, which is then accessible within Java code by using the System.getProperty() method.
`-Dfile.encoding=<encoding>`	Used to set the default file encoding. The default is usually `IBM-1047`, an EBCDIC encoding, but it is common to set this variable to `ISO-8859-1`, an ASCII encoding. For more information, see Controlling output encoding.
`-Djzos.logging={E\|W\|N\|I\|D\|T}`	This optional property can be used to control logging in the JZOS toolkit native library to the `//SYSOUT` data set. This level is independent from the launcher logging level. For more information, see Setting batch launcher logging levels.
`-Djzos.merge.sysout={true\|false}`	If set to `true`, when you run the batch launcher, the Java System.out and System.err streams are redirected to the `DD:SYSOUT` data set and `DD:STDOUT` and `DD:STDERR` statements are ignored. The default value is `false`.
`-Xms<size>`	Sets the initial Java heap size.
`-Xmx<size>`	Sets the maximum Java heap size.