How do I set the C stack size in RStudio?

I am trying to use a function spread()

from a package tidyr

in R on a data frame that contains about three million observations. It returns the following error message:

Error : C stack usage  26498106 is too close to the limit

      

        
        
        
      

    

When I run Cstack_info()

it tells me

> Cstack_info()
      size    current  direction eval_depth 
   7969177      15272          1          2 

      

        
        
        
      

    

Following the advice in the answer to this question, I tried to increase the stack size by running ulimit -s 32768

in a terminal window and opening Rstudio from the terminal.However, when I try to do this, the output Cstack_info()

does not change and when I run my code I get the same error ... Following another answer to the same earlier question, I tried updating R and Rstudio, also to no avail. What am I doing wrong here?

I am running R 3.3 on mac os x 10.12.2 with 16GB of memory.