もちば
one's post; one's position; one's station; one's place of duty
Also written 持場
Noun
交替こうたいするまで持もち場ばを離はなれるな。
Remain at your post until relieved.
どんなことがあっても持もち場ばを離はなれてはならない。
In no case are you to leave your post.