Minecraft server 1.7.2 not allocating more than 100 mb of RAM on Linux or Windows

I have tried to have a Minecraft server allocate more than the default 100MB of RAM but it wont work. With Linux I have tried running java -Xms1024M just as you have listed on your download page and it is not working. I have also tried running it through a .sh file. Then I tried on windows 7 and setup a .bat file which I had done on my 1.6.2 server. Still the server is not allocating more than 100MB of RAM.