Even at full travel, there is still an enormous amount of pressure on the control arm.
That is what a jack stand is for. You place it underneath the contol arm for support. In conjunction with the jackstand, use the jack to lift/lower the vehicle as needed to get strut arm clear of strut mount.
I will repeat Pat's statement: if you've never done this before, then it's probably best to rent a tool or have someone with more experience assist you. However, I had never done it before and found it pretty straightforward, FWIW.
'91 300E, 212K miles