I noticed shooting and sometimes walking drains stamina, how is the stamina cost calculated?

How does shooting, walking or even just holding weapon in hand drain stamina? Does weight or weapon category have effect or is every weapon set individually?

; Energy cost on weapon manipulation
; This is made out of two parts - the weapon recoil kick impact and the effort on keeping the weapon up based due to its weight.
; Weapon weight:
; The calculation of the cost is non-linear, so on lightweight guns, there is nearly no energy cost, while on very heavy guns,
; the effect is significant. This is mainly important when trying to shoulder rather heavy weaponry (LMGs, anti-material SNs),
; as those are more likely advised to be fired from hip (LMGs) or on bipod.
; Struggling with the weapon weight is reduced greatly in crouching position or if holding the gun on hip rather than shoulder.
; And it is almost or totally erased when the weapon is resting on something or you are in prone position, best with a bipod.
; The setting here represents percentage modifier to the final cost, so you can tweak it up or down as you like.
; 0 = disabled. 100 = default. Max is 250 (rather excessive).
ENERGY_COST_FOR_WEAPON_WEIGHT = 100

; Weapon recoil kick:
; This is a little different from struggling with weapon weight. It is about how much the gun "kicks" our shoulder (or hand).
; Single shots may not prove much effect, but on autofire this may incur some nasty energy loss with certain guns.
; The formula is based on weapon impact and weight, where weight actually help us out here, since it absorbs the back force
; of the recoil. Again, the cost is reduced by stance (nearly erased by bipod and/or weapon resting, greatly reduced when
; firing from hip), foregrip etc. This is mainly important if you intend to fire many long autofire bursts, when you may
; (should) consider firing from hip as a more beneficial stance for it.
; The setting here represents percentage modifier to the final cost, so you can tweak it up or down as you like.
; 0 = disabled. 100 = default. Max is 250 (rather excessive).
ENERGY_COST_FOR_WEAPON_RECOIL_KICK = 100