There is a file called /usr/include/sys/limits.h - which shows system limits (not sets them)

In there, I suspect the one you are interested in is:
/* RUN-TIME INVARIANT VALUES
The system supports the following fixed magnitude limitations.
*/
#define MAX_INPUT 512 /* max bytes in terminal
input queue, >= 256+64 */

#define NGROUPS_MAX 128 /* max number of supplementary group IDs
per process, >= 0 */

now, why it says "per process" seems unusual, what limit did you hit ?