I got one of QBP's 'locking spacers' which is sort of like a miniature seat post band clamp.
It goes directly on top of the top headset race.. it just keeps the fork in the frame.
I got it because my bike had a integrated headset, and the fork fell out, and jumbled the
various headset parts, too easily ..

when time comes to actually adjust the headset, the stem and this thing are all loosened.