There is some code in the glue init of gdc that sets these to:
```
CLASSINFO_SIZE = 19 * PTRSIZE;
CLASSINFO_SIZE_64 = 19 * PTRSIZE;
```
Which: ```(19*4)  == (0x3C+12+4)``` and ```(19*8) == (0x98)```.   Again, just a note, but maybe could remove CLASSINFO_SIZE_64.