Question about casting

I've been trying to hunt down an answer to this, and I can't seem to find one anywhere (if there's even a direct answer). After watching the video and reading all of the relevant dev posts concerning it, I still have a major question that seems to be skipped around.

Moving during casting will now interrupt it, just like it did in XI. There's a fancy little H key that will exist to force stop your character and some kind of mechanic to aid controller users, but if you are currently running, and start casting, what will happen?

To be absolutely clear, i'll use an example. Say I'm healing on CNJ and the person who is hurt is currently out of casting range. I start running toward them while mashing the heal until I am within casting range.

Now that I'm in casting range, will I...
A) Continue running and start casting (just as in XI) resulting in the spell being interrupt,
B) Automatically stop running to begin casting the spell (like XIV had originally been setup, which I thought was the absolute best improvement over XI and will likely never play a mage again if it isn't this way) to successfully cast the spell,
or C) Nothing will happen because I am still running.

As an extra tid-bit I use a controller 100% for this game, if that helps anyone answer. I am kind of expecting pre-1.18ish? where you could be running (and still holding down a movement key) and if you started casting, the casting would override your movement and you would come to a halt as you began casting. If you held down the key long enough, you would start running again (except it didn't interrupt). I could be mistaken though.