It is clearly wrong to capture the 4-byte result of LOAD and then use LLGF if the module can be AMODE 64. And, yes, the 8-byte GR0 can be used in all cases (the high half not being relevant unless AMODE 64).
As I had mentioned, the result of LOAD is suitable for use with BASSM and thus for AMODE 64 has the low bit on. If that is then used with LLGF this will be a branch to an odd address and a specification exception will result. Peter Relson z/OS Core Technology Design
