; have you editted texhdr to lower varsize?
del/q texsem.rel,texsyn.rel,texprs.rel,texext.rel,texhyf.rel,texpre.rel,texsys.rel
com texsem,texsyn,texprs,texext,texhyf
ex texpre(5000S)
\input chcode \input texpre \end
ex texsys
save arktex
save arktex
.