>>1645368called A Head or threadless stem
its based on an old motor cycle part from the 1930s
stronger than an quill stem but as you note its less adjustable
steering tubes are normaly supplyed at full length then cut shorter
A head depends on the Star nut being secure inside the steering tube
and the top nut providing enough downward force though the spacers and onto the top of the head set bearings
if the steering tube has already been cut too short the best thing would be to get a stem with greater rise and less reach
also note that A head stems can be mounted upside down to lower the handle bar hight
