I think 3 hours on the outbound is fine.

1.5 hours on the return may be cutting a little close even though its a valid connection for these reasons:

1. You're 95% likely to land on the North side of LAX coming from ANC. This requires a long taxi to T6 along 2 very busy terminals (DL and AA).

2. You'll have to walk (you can take the bus if you want but its slower) to the TBIT. It's not long but it will eat up 10 to 20 minutes and you'll have to go through security again.

3. Limited data points here, but TBIT security, even the premium lane, is slow and you could have a long long.

All these together may make for an uncomfortably close connection.