What does -xmx stand for in the java?

Hello, friend!

-Xmx indicates the maximum memory allocated during JVM running. For example, -Xms512m indicates that the JVM process can occupy a maximum of 512 MB memory. 

java -X
  -Xmixed     mixed mode execution (default)
  -Xint      interpreted mode execution only
  -Xbootclasspath:<directories and zip/jar files separated by ;>
          set search path for bootstrap classes and resources
  -Xbootclasspath/a:<directories and zip/jar files separated by ;>
          append to end of bootstrap class path
  -Xbootclasspath/p:<directories and zip/jar files separated by ;>
          prepend in front of bootstrap class path
  -Xnoclassgc  disable class garbage collection
  -Xincgc    enable incremental garbage collection
  -Xloggc:<file>    log GC status to a file with time stamps
  -Xbatch        disable background compilation
  -Xms<size>      set initial Java heap size
  -Xmx<size>      set maximum Java heap size
  -Xss<size>      set java thread stack size
  -Xprof        output cpu profiling data
  -Xfuture       enable strictest checks, anticipating future default
  -Xrs         reduce use of OS signals by Java/VM (see documentation)
  -Xcheck:jni      perform additional checks for JNI functions
  -Xshare:off      do not attempt to use shared class data
  -Xshare:auto     use shared class data if possible (default)
  -Xshare:on      require using shared class data, otherwise fail.

Hope this helps!

If you want to know more information about -Xmx, See What's the difference between XMX, XMS and XSS in JVM?

Hello,

In Java, -Xms sets the initial Java heap size, while-Xmx sets the maximum Java heap size.

e.g,
# Start with 128MB of memory, and allow the Java process to use up to 1024MB of memory.
java -Xms128m -Xmx1024m
# Start with 256MB of memory, and allow the Java process to use up to 4G (4096MB) of memory.
java -Xms256m -Xmx4g