The criterion of stress applies only to nominal compounds, and the distinction between compound and idiom becomes fuzzy for verbs and other nominal categories.
Compounding
Compounding refers to the faculty and device of language to form new words by combining or putting together old words.
Compounds are stems consisting of more than one root, e.g. bedside, blackbird, by-effect, rainbow, waste paper basket. Compounding is a very common and frequent process for enlarging vocabulary.
However, in addition to the semantic criterion, we may also use involving order.
In a verb plus adverb compound like forthcoming, there is a clear difference in order between the phrases from which they derive (e.g. come forth) and the resultant compound.
From the root ced (and its variant form cess), ‘go, yield,’ are derived abscess, accede, accessory, ancestry, antecedent, cease, cede, concession, decease, exceed, excessive, incessant, intercede, precede, predecessor, proceed, recede, recess, succeed ….