As the Data folder is prone to being wiped every game update. We HIGHLY recommend you package your generated worlds inside of a template modlet that is loaded server-side. This is very easy to do and makes it so long as you keep this mod and the game updates don't break you will be able to play for a good while. Inside of your Mods folder create another folder with a unique name "MyGeneratedWorlds"

Inside of the folder MyGeneratedWorlds we will now create two XML files for our mod. They will be nearly identical. The first is ModInfo.xml you can use this template, but change out your important details as below:

<?xml version="1.0" encoding="UTF-8" ?>
<xml>
  <ModInfo>
    <Name value="MyGeneratedWorlds" />
    <Version value="19.2" />
  </ModInfo>
</xml>

Name value must match the folder you created for the mod. Version Value must match the version the generated world was created in.

The next xml file will be mod.xml just follow the format below:

<?xml version="1.0" encoding="utf-8"?>
<mod>
  <info>
    <name>MyGeneratedWorlds</name>
    <mod_version>19</mod_version>
  </info>

</mod>

Now that are files are created we can now create another new folder. This folder will be called Worlds once the folder is created any generated map you create can be placed inside and loaded onto the server under the option Custom Map found under the "Advanced" tab.

When generating a world keep in mind your target and your server's health. As it has been tested worlds over 12k have been highly unstable and are recommended against.