# Non-Standard Options of the Classic VM

> The Java 2 Classic VM is included only in the Java 2 SDK. It is not included in the Java 2 Runtime Environment.
> -Xbootclasspath:bootclasspath
>   Specify a semicolon-separated list of directories, JAR archives, and ZIP archives to search for boot class files. These are used in place of the boot class files included in the Java 2 SDK. Note: Applications that use this option for the purpose of overriding a class in rt.jar should not be deployed as doing so would contravene the Java 2 Runtime Environment binary code license.

> -Xbootclasspath/a:path
>   Specify a semicolon-separated path of directires, JAR archives, and ZIP archives to append to the default bootstrap class path.

> -Xbootclasspath/p:path
>   Specify a semicolon-separated path of directires, JAR archives, and ZIP archives to prepend in front of the default bootstrap class path. Note: Applications that use this option for the purpose of overriding a class in rt.jar should not be deployed as doing so would contravene the Java 2 Runtime Environment binary code license.

> -Xdebug
>   Start with the debugger enabled. The Java interpereter prints out a password for jdb's use. Refer to jdb description for more details and an example.

> -Xnoclassgc
>   Disable class garbage collection

> -Xms n
>   Specify the initial size of the memory allocation pool. This value must greather than 1000. To multiply the value by 1000, append the letter k. To multiply the value by 1 million, append the letter m. The default value is 1m

> -Xmx n
>   Specify the maximum size of the memory allocation pool. This value must greather than 1000. To multiply the value by 1000, append the letter k. To multiply the value by 1 million, append the letter m. The default value is 64m.

> -Xrunhprof[:help][:<suboption>=<value>,...]
>   Enables cpu, heap, or monitor profiling. This option is typically followed by a list of comma-separated "<suboption>=<value>" pairs. Run the command java -Xrunhprof:help to obtain a list of suboptions and their default values.

> -Xrs
>   Reduce the use of operating system signals.

> -Xcheck:jni
>   Perform additional checks for Java Native Interface functions.

> -Xcheck:nabounds
>   Perform additional checks for Java Native Interface array bounds.

> -Xfuture
>   Perform strict class-file format checks. For purposes of backwards compatibility, the default format checks performed by the Java 2 SDK's virtual machine are no stricter than the checks performed by 1.1.x versions of the JDK software. The -Xfuture flag turns on stricter class-file format checks that enforce closer conformance to the class-file format specification. Developers are encouraged to use this flag when developing new code because the stricter checks will become the default in future releases of the Java application launcher.