Not that I could find, unfortunately. My gcmh-low-cons-threshold is at 800000 and gcmh-high-cons-threshold is at 134217728.

Here is the gdb stuff:

(gdb) x/32gx 0xffdf600
0xffdf600: 0x0000000000000000 0x000000000000b640
0xffdf610: 0x0000000000000000 0x0000000000019082
0xffdf620: 0x0000000000019102 0x000000000000004e
0xffdf630: 0x0000000000000000 0x0000000000000192
0xffdf640: 0x0000000000000002 0x0000000000000000
0xffdf650: 0x400000002300000d 0x0000000000000000
0xffdf660: 0x000000000544a480 0x00000000019e1500
0xffdf670: 0x0000000000000000 0x000000000000b640
0xffdf680: 0x0000000000000000 0x0000000000019082
0xffdf690: 0x0000000000019102 0x000000000000004e
0xffdf6a0: 0x0000000000000000 0x0000000000000192
0xffdf6b0: 0x0000000000000002 0x0000000000000000
0xffdf6c0: 0xc000000004002001 0x000000003b67f833
0xffdf6d0: 0x0000000024f854e0 0x000000001cff54f0
0xffdf6e0: 0x0000000000000002 0x00000000249d0eb3
0xffdf6f0: 0x0000000018e40e25 0x000000003a8fa9c0
(gdb) p $rsp
$15 = (void *) 0x7fffffff5b10
(gdb) p globals.f_gc_cons_threshold
$16 = 800000
(gdb)     p globals.f_string_chars_consed
$17 = 144457277695
(gdb)     p &globals.f_gc_cons_threshold
$18 = (intmax_t *) 0xcf4278 <globals+4056>
(gdb) p (struct Lisp_String *)0x000000001cfbfe40
$19 = (struct Lisp_String *) 0x1cfbfe40