Leave a stack bigger than 64 in a chest, hit sort, observe as quark copies over the entire stack into the first empty slot, while subtracting only 64 items from the original stack.
Versions:
Quark r1.5-145
Stackup 0.2.3
Forge 2768
Misc: https://github.com/Cyprex/tgs-minecraft

Closing due to asiekierka no longer maintaining their 1.12 mods, VazkiiMods/Quark#1101