This statement specifies the number of concurrent system threads.
Definition
A lower-level DBH option of SYSTEM-LIMITS
Function
System threads are created in order to deal with internal system requests to the spaces. The lower-level DBH option SYSTEM-THREADS specifies the number of these system threads.
In the case of the linked-in DBH, the DBH option SYSTEM-THREADS is ignored; the default value of 1 applies to WRITE-THREADS.
You can adjust the value of the option with the administration statement RELOAD-DBH-SESSION (see "RELOAD-DBH-SESSION") when the DBH modules are reloaded.
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Operands
SYSTEM-THREADS = *STD
Specifies the maximum number of concurrently active system threads. The default values are described under *PARAMETERS.
SYSTEM-THREADS = *PARAMETERS(...)
WRITE-THREADS =
Specifies the maximum number of concurrent system threads that deal with open write requests to the spaces. These system threads are known as write threads.
WRITE-THREADS = *STD / <integer 1..512>
You can specify the number of write threads independently of the number of threads specified by means of the DBH option THREADS.
However, the default value is obtained from the number of threads divided by 32. If this calculation does not produce an integer, the figure is rounded up to the next integer.
The size of the value specified for the WRITE-THREADS operand has the following effects:
If a very low number is selected, the TA-LOG files will be larger than expected. The CPU requirements will be considerably increased. As a result the writing of the after-images, as specified in the option RESTART-CONTROL, may no longer be guaranteed.
A very high value, on the other hand, affects the address space requirements rather than the CPU requirements.
Information on system threads
You will find information on the number of concurrent system threads in the “SYSTEM THREADS” form of the SESAM/SQL monitor SESMON (see "DBH form SYSTEM THREADS").