Should a peer review for an academic journal include a recommendation for acceptance? I have been asked to review an article for an academic journal for the first time. The accepted answer to Scope for the role of peer reviewer as well as this post have given me a good idea of what to include and how to structure my review already. 

What I find not mentioned in either post (but somehow seem to have it in the back of my head) is, whether I should include a recommendation to the editor about accepting the paper or not? I.e. a short line such as I deem the paper [not] suitable for publication in [journal name].

Or is this more complicated and I should include such a statement only if I have a strong opinion for or against the paper I review and otherwise leave it up to the editor? 

In my case there is no template or instructions for the review given by the editor/journal. The field, if it matters, could be mathematics or economics.
Remember that the final decision is always up to the editor regardless of your recommendation. And (hopefully) the editor reads your entire review, not just the recommendation.

I usually include a recommendation in my reviews, but I always try to justify it thoroughly, so that the recommendation itself is essentially a redundant summary of what I have already said. If I do not have a strong opinion either way, I will say so.