%% 
%%  A DANTE-Edition example
%% 
%%  Example 05-04-2 on page 173.
%% 
%%  Copyright (C) 2010 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% 
%% ==== 
% Show page(s) 1,2
%% 
\documentclass[]{article}
\pagestyle{empty}
\setlength\textwidth{183.78818pt}
\usepackage[utf8]{inputenc}% adapt maybe
\usepackage[paper=70mm:90mm,pagesize]{typearea}
\usepackage[utf8]{inputenc}% adapt maybe
\areaset{50mm}{58mm}
\setlength\parindent{0pt}
\newcommand\demoText{In theory, the definition of the table environment could be
extended to integrate the \protect\texttt{\textbackslash need} command. These two
examples show the first two pages of a document, where the first page has
(without \protect\texttt{\textbackslash need}) or does not have (with
\protect\texttt{\textbackslash need}) a page break.}
\setlength\emergencystretch{1.5em}
\usepackage{fancyhdr}
\lhead{\small\texttt{need} demo}
\pagestyle{fancy}
\usepackage[english]{babel}
\setcounter{page}{1}
\renewcommand\thepage{page \arabic{page}}

\usepackage{supertabular}
\makeatletter
\newcommand\need[1]{\par \penalty-100 \begingroup % preserve \dimen@
  \dimen@\pagegoal \advance\dimen@-\pagetotal % space left
  \ifdim #1>\dimen@ % not enough space left
%    only do \vfil if some space left on page
     \ifdim\dimen@>\z@ \vskip -\pagedepth plus 1fil \fi
     \break
  \fi \endgroup}
\makeatother

\begin{document}
\section{A table}
\demoText% see other example
\need{6\normalbaselineskip}
\begin{center}
\tablecaption{Caption.}
\tablehead{\hline column1 & column2 \\}
\begin{supertabular}{|cl|cl|}\hline
  yyy & xxx \\\hline yyy & xxx \\\hline yyy & xxx \\\hline
\end{supertabular}
\end{center}
\end{document}