H. Today I found the same trouble with the template that provides the website of the JUCS. After many tests, the appropriate solution was to install the package "apalike". Interestingly, the first test was on the template that JUCS provides to work and the format of the references was not in the appropriate format such as the journal requires. However, I did a simple document with one citation and I compile the document, the editor ask me for install the package "apalike", I clicked yes, the result was successfully. So, I did the same on the template and I a got it.
Example of the code:
My citation....
\cite{Alemdar2015}
The last paragraph in the template
\section{Conclusions and Future Work}
Until recently, focus in metadata research has focused on what
metadata is and how it should be represented to the user...
the bibliography section with parameters
\bibliographystyle{apalike} %the style for JUCS
\bibliography{mybib} % the file containing my bibliography
The original bibliography of the template (commented)
%\begin{thebibliography}{5}
%
%\bibitem[Anderson and Reich 2000]{sc2-proc} Anderson, K., Reich,
%S. (eds.): ``Proceedings of the Second Workshop on Structural
%Computing''; Lect. Notes Comp. Sci. 1903, Springer, Berlin.
%
%\bibitem[Christodoulakis et~al. 1999]{callimachus} Christodoulakis,
Best regards