TUNE
The TUNE option specifies the architecture
for which the executable program will be optimized.
Default is: The default TUNE level matches the ARCH level if
ARCH is specified. If ARCH is not specified, both
ARCH and TUNE default to 10.
Abbreviations are: None
- 10
- Generates code that is optimized for the 2827-xxx (IBM® zEnterprise® EC12) and 2828-xxx (IBM zEnterprise BC12) models in z/Architecture® mode.
- 11
- Generates code that is optimized for the 2964-xxx (IBM z13®) and 2965-xxx (IBM z13s®) models in z/Architecture mode.
- 12
- Generates code that is optimized for the 3906-xxx (IBM z14) and 3907-xxx (IBM z14 ZR1) models in z/Architecture mode.
- 13
- Generates code that is optimized for the 8561-xxx (IBM z15) and 8562-xxx (IBM z15 T02) models in z/Architecture mode.
- 14
- Generates code that is optimized for the 3931-xxx (IBM z16) model in IBM z/Architecture mode.
TUNE option specifies the architecture for which the executable program will
be optimized. The TUNE level controls how the compiler selects the available
machine instructions, while staying within the restrictions of the ARCH level in
effect. The TUNE option does so to provide the highest performance
possible on the given TUNE architecture, choosing from the instructions allowed by
the given ARCH level.TUNE impacts performance only; it
does not impact the processor model on which you will be able to run your application.Select TUNE to match the architecture of the machine where your application will
run most often. The TUNE level must always be greater or equal to the
ARCH level because you will want to tune an application for a machine on which it
can run. The compiler enforces this by adjusting TUNE up rather than
ARCH down. TUNE does not specify where an
application can run and it affects optimization only.
For example, if you have production machines that are z15® and disaster recovery (DR) machines that are z14, you should compile with
ARCH(12) and TUNE(13). In this way, your programs will run well on
the DR machines and run as fast as possible in production.
TUNE level is lower than the specified ARCH
level, the compiler adjusts the TUNE level to match the ARCH
level.