“Stress on” is commonly misused to mean “to experience stress” as in “I’m stressing on the term paper I have to do.” Still informal, but better, is “I’m stressed about. . . .” In a more formal context you could express the same idea by saying “I’m anxious about. . . .”
It is perfectly fine, however, to say that you place stress on something, with “stress” being a noun rather than a verb.