You can add struts to the beginning and end of your columns as follows:
\documentclass{article}
\usepackage{tabu}
\usepackage{longtable}
\pagestyle{empty}
\newcommand{\aefrontstrut}{\rule{0pt}{0.8\baselineskip}}
\newcommand{\aebackstrut}{\rule[-0.6\baselineskip]{0pt}{0.8\baselineskip}}
\begin{document}
\begin{longtabu} to \linewidth {| m{0.41\textwidth} | >{\aefrontstrut}m{0.53\textwidth}<{\aebackstrut} |}
\hline
\multicolumn{1}{|c}{Static (stuff)} & \multicolumn{1}{|c|}{Dynamic (stuff)} \\ \hline
\endhead
\hline
\endfoot
\endlastfoot
textetxtetxtexttext & textetxtetxtexttext$-$Buffer: X\textbackslash Y\textbackslash y\textbackslash G\textbackslash X\textbackslash H\textbackslash J\textbackslash x00$-$\\ \hline
textetxtetxtexttext & textetxtetxtexttext$-$Information: XYZ\textbackslash x00 ???\\ \hline
\caption{calls}
\label{tab:alls}%
\end{longtabu}
\end{document}
You can use LaTeX's own \strut command, or you can make your own customized struts as I've done above. By using two different style struts and the > and < modifiers for columns, you can control the spacing above the first line and after the last line in that column.

By changing the height of the first strut and the depth of the second strut, you can finely control the spacing.
\rule[<raise>]{<width>}{<height>}
Technically, the optional argument to \rule is not the depth; it's a dimension by which the rule is raised or lowered. By using a negative value you are essentially setting the depth of the strut. Since the strut should not be visible, make sure the <width> is set to Opt.
UPDATE
As noted in the comments below, the alignment can be off if the last column contains some short text. To get around this, use the > < directives for both columns:
\begin{longtabu} to \linewidth {| >{\aefrontstrut}m{0.41\textwidth}<{\aebackstrut} | >{\aefrontstrut}m{0.53\textwidth}<{\aebackstrut} |}
\baselineskipsometimes gets messed with by authors who need to change the line spacing of their documents. (I know, they really shouldn't be affecting the line space by modifying\baselineskip, but enough people seem to do it anyway to make this a problem to be reckoned with.) To increase the generality/robustness of your answer, you may want to express the heights and depths of the struts as multiples of a font-related parameter such asexrather than as multiples of\baselineskip. – Mico Aug 18 '13 at 16:23