The chunk is 16x16x256, the area above you (and under you) is loaded when you're in the chunk (and pretty much every other chunk that is loaded within your render distance (or by using optifine's far loading which lets you load far more chunks than your render distance),
Need a few questions answered, First off Is a chunk TECHNICALLY 16x16x16 or 16x16x256
Aka does the area above you unload
Second
If I needed a chunk loader, would it apply to 16x16x256 and not just a 16x16x16 area
It's just 16x16.
No height.
The chunk is 16x16x256, the area above you (and under you) is loaded when you're in the chunk (and pretty much every other chunk that is loaded within your render distance (or by using optifine's far loading which lets you load far more chunks than your render distance),
I'm just a very boring person.