Potential Problems that Can Arise When You Use Teraspace

When you use teraspace in your programs, you should be aware of the potential problems that can arise.

If you create programs using the TGTRLS(V5R4M0) parameter, be careful not to develop a dependency on passing teraspace addresses to other programs unless all these other programs can handle teraspace addresses. All programs that run on IBM® i 6.1 or later can use teraspace addresses.
Some MI instructions cannot process a teraspace address. An attempt to use a teraspace address in these instructions causes an MCH0607 exception.
- SCANX (only some options are limited)
Effective Address Overflow (EAO) can impair performance. This situation can occur in certain code generated for a processor prior to POWER6. See Adaptive Code Generation. Specifically, an EAO can occur during an address computation on a 16-byte pointer, when the result is a teraspace address value that is less than the 16 MB boundary lower than the start address. A hardware interrupt is generated that is handled by the system software. Many such interrupts can affect performance. Avoid frequent teraspace address calculations that compute a smaller value in a different 16 MB area. Or, create your program with the MinimizeTeraspaceFalseEAOs LICOPT, as described in Licensed Internal Code Options.