Server freezing and crashing beacuse of an average tick taking over 60 seconds

I have created myself a vanilla server (a normal, .jar one) on a 16w03a snapshot version. I made a batch file, that would run the server for me (i added some more code, to ask me, to check connetions, restart the server, etc., i have the copy in the attachment), and after running the server, it just freezes. I attached here the crash log, and the batch file i made. Just right click it, and press Edit (Arisa deleted that file, nevermind). I used from 512M to 1024M. I tried to get more (1G to 2G), but it won't let me.
(Error ocurred while initialisation of VM
Could not reserve enough space for 2097152KB object heap)
What an awkward error...