IK on torso spazzes out

I’m applying inverse kinematics to my rig and the slightest of mouse cursor movements cause it to go crazy:

I don’t understand why this is happening.

using Blender 2.78 on Windows.

EDIT: silly me. I forgot to make a control bone for IK. My bad. Please delete this thread, it’s so a dumb mistake that it isn’t worth keeping around.