Description: Before z/OS V2R1, through PARMLIB member LOADxx you could enable that CPUs be added to the configuration over the life of the IPL if the hardware supported such addition. The default was for all CPUs that could be configured to the LPAR, which was the minimum supported by the z/OS release (for example, 100) and the machine (for example, 80), and which could be asked for explicitly by DYNCPADD ENABLE. In z/OS V2R1, the LOADxx keyword DYNCPADD now supports a 1-4 character decimal value nnnn that indicates how many CPUs z/OS is able to dynamically add over the life of the IPL. The default has changed to 16.
Element or feature: | BCP. |
When change was introduced: | z/OS V2R1. |
Applies to migration from: | z/OS V1R13 and z/OS V1R12. |
Timing: | Before the first IPL of z/OS V2R1. |
Is the migration action required? | Yes, if the LOADxx DYNCPADD value is omitted (defaulted) and the default number of CPUs (16) z/OS will be able to dynamically add over the life of the IPL is not sufficient. Recommended, if you specify DYNCPADD ENABLE, which provides maximum flexibility but also results in maximum storage usage and overhead. |
Target system hardware requirements: | All system z hardware (z10 EC/BC and later hardware) that supports dynamic CPU addition. |
Target system software requirements: | None. |
Other system (coexistence or fallback) requirements: | When specifying the maximum number of CPs that z/OS can dynamically add with LOADxx DYNCPADD nnnn, this LOADxx cannot be shared with pre-V2R1 systems; that is, the nnnn parameter of DYNCPADD is not recognized by pre-V2R1 systems. |
Restrictions: | None. |
System impacts: | Specifying DYNCPADD nnnn or taking the DYNCPADD 16 default allows z/OS to determine the number of CPUs that z/OS must be prepared to be dynamically added for the life of the IPL. Because z/OS can know the maximum CPU id that can be dynamically added for the life of the IPL at IPL, z/OS can obtain CPU array related storage based on the maximum number of CPUs that can be activated for the life of the IPL. |
Related IBM® Health Checker for z/OS® check: | None. |