# [Tex/LaTex] Length parameter for vertical skip space in a math environment

I learned here that I can use \\[<len>] to explicitly set the vertical skip space between lines, e.g., <len> set to 3ex. I'd like to set <len> to, say, 2-times the normal length in this environment (e.g., align or dcases) but I don't know the length parameter that determines this.

Another example: I'd like to change the explicit 3ex below to some multiple of the vertical line-skip space in the align environment. Does anyone know what that is?

\documentclass{beamer}
\usepackage{amsmath}
\usepackage{mathtools}
\begin{document}
\begin{frame}
Some sample text
\begin{align*}
\pi(\mu \mid x) &= \frac{\pi(\mu)\,\mathcal{L}(x \mid \mu)}{p(x)} \\
&= \begin{dcases*}
\frac{(1-w)\phi(x)}{p(x)} & for $$\mu=0$$ \\
\frac{w\gamma(\mu)\phi(x-\mu)}{p(x)} & for $$\mu \neq 0$$.
\end{dcases*}
\end{align*}
\end{frame}
\end{document}


use multiples of \baselineskip and in tabulars/arrays \normalbaselineskip

\documentclass{scrartcl}
\usepackage{mathtools}

\begin{document}

\frac{(1-w)\phi(x)}{p(x)} & for $$\mu=0$$ \\
\frac{w\gamma(\mu)\phi(x-\mu)}{p(x)} & for $$\mu \neq 0$$.