Hi Keith,
This looks like the same issue first report HERE and logged as TPR#18937. The good news is that a fix will be available in 12.10 which will be available very soon.
- Mat
% pgf90 pack.f90 -V12.9
% a.out
0
Segmentation fault
% pgf90 pack.f90 -V12.10
% a.out
0
1
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0