ansi 15.6.2.1020
<TOOLS>
roll 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-ROLL
would 2ROLL a DP-mark and a COMP-magic, see ROLL
reference: p4_cs_roll in ../src/toolkit.c:0296, export CO CS-ROLL