This patent notes in passing:
It may be necessary to add $\ce{NaOH}$ to stabilize aqueous $\ce{NaCN}$. Anyone skilled in the art would know the amount of $\ce{NaOH}$ to add.
Obviously I'm not skilled in the art. I assume the stabilization is against hydrolysis. What is the mechanism by which $\ce{NaOH}$ would stabilize aqueous $\ce{NaCN}$, and how would one determine the correct amount of $\ce{NaOH}$ to add?
(I'm expecting it's some target pH level, but I'm too far along my "assumption" chain to know what the issues are.)