Xms size must be multiple of 1024

 from java (oracle.com) and java (oracle.com):

-Xmssize

Sets the minimum and the initial size (in bytes) of the heap. This value must be a multiple of 1024 and greater than 1 MB. Append the letter k or K to indicate kilobytes, m or M to indicate megabytes, g or G to indicate gigabytes.

The following examples show how to set the size of allocated memory to 6 MB using various units:

-Xms6291456
-Xms6144k
-Xms6m

Also for 

-Xmxsize

Specifies the maximum size (in bytes) of the memory allocation pool in bytes. This value must be a multiple of 1024 and greater than 2 MB. Append the letter k or K to indicate kilobytes, m or M to indicate megabytes, g or G to indicate gigabytes. The default value is chosen at runtime based on system configuration. For server deployments, -Xms and -Xmx are often set to the same value. See the section "Ergonomics" in Java SE HotSpot Virtual Machine Garbage Collection Tuning Guide at  http://docs.oracle.com/javase/8/docs/technotes/guides/vm/gctuning/index.html.

The following examples show how to set the maximum allowed size of allocated memory to 80 MB using various units:

-Xmx83886080
-Xmx81920k
-Xmx80m

The -Xmx option is equivalent to -XX:MaxHeapSize.