Enabling LPAR CPU management

Once you have defined the SYSZWLM_xxxxyyyy coupling facility structure, the remaining actions you need to take to enable LPAR CPU Management will all occur on the hardware management console (HMC).

In the Primary Support Element Workplace, make sure that Not dedicated central processors is selected in the activation profile of each logical partition. This ensures that the logical partition will use shared CPs instead of dedicated CPs. On the same panel, specify the initial and reserved number of logical CPs you wish to have available to each logical partition. Production partitions which potentially need access to the full power of the CPC should be defined with the maximum number of logical CPs (equal to the number of shared physical CPs). Other partitions can be defined with a fewer number of logical CPs if they need less power, or if you wish to specifically restrict them to less power. At a minimum, the number of logical CPs should be sufficient to achieve the partition's maximum weight.
For some logical partitions, you may not need to make any of those changes, as the settings are already correct. If you do need to make any of those changes, note that you'll need to deactivate and then reactivate the logical partition for the changes to take effect. For the remaining actions, you will not need to do this after making changes.
For each logical partition that will participate in LPAR weight management, do the following:
- Make sure that Initial Capping is turned off. WLM cannot manage the weight of a logical partition that is capped.
- Enter the initial processing weight. This becomes the logical partition's weight when it is first IPLed.
- Enter the minimum and maximum weights. These set the lower and upper limits for the weights that WLM will assign to the logical partition.
- Check the WLM Managed box. This is the final step in activating LPAR weight management.

Once you have made those changes for z/OS® images, you do not have to do anything else to activate VARY CPU management. You can disable VARY CPU management, if you wish, by adding the keyword VARYCPU=NO to the IEAOPTxx parmlib member and then issuing the SET OPT=xx command to activate the change. The scope of this command is by single system. If there are multiple systems in the LPAR cluster, then the other systems will continue to use VARY CPU management. You can set VARYCPU=YES to return the system to VARY CPU management. Note that if any CPs were taken offline by an operator, those CPs will need to be configured back online before they can again be managed by VARY CPU management.