The launcher help text for -Xms is wrong and should be updated to match the manpage description. The actual meaning of -Xms is that it sets both the initial and minimum Java heap size, not just the initial Java heap size.

$ java -X
...
-Xms<size> set initial Java heap size

From the manpage:

`-Xms` *size*
: 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, or `g` or `G`
    to indicate gigabytes. The following examples show how to set the size of
    allocated memory to 6 MB using various units:

The launcher help text likely needs to be updated for all localizations as well.