8.98 MAXCPU (
Display or set maximum number of CPUs)
8.98.1 Function
The MAXCPU command displays or sets the maximum number of installed processor engines. The com-
bination of MAXCPU and NUMCPU controls the behaviour of how many CPU engines will be configured
online upon startup and how many can be configured online later. The NUMCPU statement specifies the
number of engines which will be configured online at startup time. All processors are CP engines unless
otherwise specified by the ENGINES statement.
MAX_CPU_ENGINES is a compile-time variable which sets an upper limit on the value of MAXCPU. The
value of MAX_CPU_ENGINES is displayed in the build information message on the Hercules control
panel at startup time. To change the value of MAX_CPU_ENGINES you must rebuild Hercules. For Unix
builds, specify "./configure --enable-multi-cpu=nn" before performing make. For Windows builds, specify
"SET MAX_CPU_ENGINES=nn" before performing nmake.
MAX_CPU_ENGINES may be up to 128 on 64-bit Linux platforms. On Windows, and on all 32-bit plat-
forms, the maximum value is 64. For performance reasons, values above 32 are not recommended for
32-bit platforms. If MAX_CPU_ENGINES is set to 1 then multiprocessing is disabled. See also the NUM-
CPU statement for a discussion of the performance implications of MAX_CPU_ENGINES.
The value of MAXCPU cannot exceed the value of MAX_CPU_ENGINES. If MAXCPU is not specified in
the configuration file, then its initial value is equal to NUMCPU. If MAXCPU and NUMCPU are both omit-
ted, then MAXCPU is set to 1.
Given without an argument the MAXCPU statement displays the current maximum number of installed
processor engines.
For detailed explanations on the interrelationship between MAXCPU, ENGINES and NUMCPU please
see “
8.98.2 Syntax
Descriptive
[nn]
Diagram
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nn
8.98.3 Parameter
nn
Specifies the maximum number of installed processor engines. The value of
MAXCPU cannot exceed the value of MAX_CPU_ENGINES.
