Options JVM screen

This screen allows you to configure the JVM options used when starting ZAP.

JVM Options

The option was added so that the Java maximum memory allocation pool size can be set, which is of the form: -Xmxn where n is the size in bytes.
Good values for this field could be:

• -Xmx256m
• -Xmx512m
• -Xmx1024m

Unlike the other ZAP options these are held in the file .ZAP_JVM.properties in the user's default ZAP directory, which depends on the OS being used, for example:

• Windows 7/8: C:\Users\<username>\ZAP
• Windows XP: C:\Documents and Settings\<username>\ZAP
• Linux: ~/.ZAP
• Mac OS: ~/Library/Application Support/ZAP

Windows Notes: These options are not used when starting ZAP via the executable. The directory where the file .ZAP_JVM.properties is located depends on the environment variable %USERPROFILE%.

JVM Memory Details

• Size - the amount of memory currently allocated to the JVM.
• Used - the amount of currently allocated memory used (not free).
• Max - the amount of memory that the JVM could grow to occupy.

Generally max should be close to -Xmx (if specified). However, the following behavior was observed during testing under Java 8 on Windows OS.

-Xmx512m was specified (which should calculate out to ~488MiB), however, 455.5MiB was displayed.
-Xms512m -Xmx512m was specified, however, 475MiB was displayed.
-XX:+AlwaysPreTouch -Xms512m -Xmx512m, and 474.5MiB was displayed.

So it seems the JVM does some calculation/manipulation at execution which may mean that the results may not align as expected for the options the user inputs (this is a JVM issue, not a ZAP issue).

See also

External links