Does Gforth optimize proper tail calls?

Question

I have the following (somewhat inefficient) code:

\ RNG support

VARIABLE seed

: rand ( -- random )
seed @
DUP 13 LSHIFT XOR
DUP 17 RSHIFT XOR
DUP 5 LSHIFT XOR
DUP seed ! ;

\ Checker for number of set bits

: clear-lsb ( u -- u )
DUP 1- AND ;

: under++ ( u x -- u++ x )
SWAP 1+ SWAP ;

: ones-rec ( c u -- c u | c )
?DUP ( c 0 | c u u )
0<> IF EXIT ( c | c u )
THEN under++ clear-lsb RECURSE ;

: ones-rec ( c u -- c u | c )
?DUP IF
under++ clear-lsb
RECURSE
THEN ;

: ones ( u -- n )
0 SWAP ones-rec ;

\ Makes a random number with n set bits

: rand-n-bits ( n -- random )
rand ( n random )
OVER SWAP ( n n random )
ones ( n n bits )
= ( n f )
IF EXIT
THEN RECURSE ;

By my understanding, both the RECURSEs in rand-n-bits and ones-rec should be proper tail calls. However, when I ask Gforth to do 10 rand-n-bits, I overflow the return stack. Does Gforth not optimize proper tail calls, or am I simply not doing this correctly?