here is the same line:

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

Is the 128, the number of groups a user can belong to? I'm assuming the "group IDs per process" is actually groups per user.

On our server, 16 groups is the maximum for any given user. We were told that we can adjust this number to 32, but where is this setting?