next phase

git-svn-id: https://svn.r-project.org/R/trunk@63219 00db46b3-68df-0310-9c12-caf00c1e9a41
simpler version

git-svn-id: https://svn.r-project.org/R/trunk@63220 00db46b3-68df-0310-9c12-caf00c1e9a41
and add stack check

git-svn-id: https://svn.r-project.org/R/trunk@63221 00db46b3-68df-0310-9c12-caf00c1e9a41
malloc would do here

git-svn-id: https://svn.r-project.org/R/trunk@63222 00db46b3-68df-0310-9c12-caf00c1e9a41