What is considered credible evidence in computer science? Is it books or lab reports or technical reviews or something completely different?
It depends on exactly what kind of thing you're researching, but the gold standard evidence would be source code. This allows anyone to see your code and run it on their own machine, see exactly how the machine is operating, and they can draw their own conclusions.

If you can't provide your source code for whatever reason, you can still have well thought out experiments whose methodology and results are described in conference or journal papers.

In terms of academic credit or progressing towards your degree, the basic unit of scholarly merit in computer science is the conference paper rather than the journal paper. In many fields it's the opposite, where conference papers don't count for much and journal papers are the goal. In CS we still have journal papers that are often published as extensions to a conference paper, and this is an opportunity to address any initial concerns from the community or extend and round out a contribution. These are worthwhile endeavors, especially if the conference paper is highly regarded, but they're not the norm.

This changes some things and doesn't change other things. For example, I know of colleagues in fields where conference papers don't count for anything, but in those fields the conferences are not peer reviewed and essentially a good enough sounding abstract is enough to get accepted to a conference. They still publish rigorous peer reviewed works, but they do those in journals that are not associated with any specific conference.