\documentclass[tikz]{standalone}
-%\usepackage{listings}
-%\lstset{%
-% basewidth=0.5em,
-% basicstyle=\tt\scriptsize,
-% breakatwhitespace=false,
-% breaklines=true,
-% captionpos=b,
-% columns=[c]fixed,
-% commentstyle=\sl,
-% escapeinside={[+}{+]}, % chktex 9
-% frame=,
-% keepspaces=true,
-% keywordstyle=\bf,
-% showspaces=false,
-% showstringspaces=false,
-% showtabs=false,
-% stringstyle=\it,
-% tabsize=4,
-% numberstyle=\tiny,
-% language=C,
-%}
\usetikzlibrary{arrows.meta,shapes.symbols,matrix,positioning}
\begin{document}
\begin{tikzpicture}[%
\matrix (main) [memory] {
& |[descr]| {\rm high addresses} \\
& || heap\\
- & || $\downarrow$\\
+ & || {\normalsize $\downarrow$}\\
& || \ldots\\
- & || $\uparrow$\\
+ & || {\normalsize $\uparrow$}\\
& || stack\\
- & || $\uparrow$ \\
+ & || {\normalsize $\uparrow$}\\
& || tasks \\
& |[descr]| {\rm low addresses}\\
};