I've inherited some F77 code from the 1980s that I'd like to eventually use in an R package that is on CRAN. Basically I'll be substituting a slow function written in straight R with a .Call to a F77 subroutine that runs 100x faster. I've done similar heavy lifting with C in the past. However, when I compile the fortran subroutine via R CMD SHLIB I get a warning about one of the arrays being "larger than limit set by '-fmax-stack-var-size='". I can fix this by compiling explicitly with gfortran and setting -fmax-stack-var-size appropriately. However, how can I set the flag when running R CMD SHLIB? In a Makevars file? Eventually, I'll include this in a new release and submit to CRAN and I want to head off any issues. Many thanks.