ansi 15.6.2.1015
<TOOLS>
pick a value in the compilation-stack - note that the compilation
stack _can_ be seperate in some forth-implemenations. In PFE
the parameter-stack is used in a double-cell fashion, so CS-PICK
would 2PICK a DP-mark and a COMP-magic, see PICK
reference: p4_cs_pick in ../src/toolkit.c:0283, export CO CS-PICK