I believe the Stop-Loss program was put to an end by the Obama administration. If you're wounded to the point where a medical board determines that you cannot complete the specific duties assigned to you, then you will receive an honorable or medical discharge. This includes mental disabilities. The military, especially the Army, is putting a HUGE amount of time into combat mental disorders such as PTSD nowadays, so if, down the line, you start to feel suicidal, or start to experience other issues such as flashbacks, anxiety, etc, DO NOT HESITATE to take the precautions that are offered to you by the military.
EDIT: I looked it up, and the Stop-Loss program is not being put to an end, but rather SIGNIFICANTLY reduced. So by the time you're done with your 4 year military contract, the program will probably be done with.