Because global resource serialization supports two types of complexes, a star or a ring, it is possible that due to an error in the specification of the GRS= parameter, the installation could accidentally try to IPL a system into the wrong type of complex. The possible error and the action taken by global resource serialization in each are as follows:

• If an MVS™ system is IPLed with one of the ring-related parameters (GRS=START, JOIN, or TRYJOIN) and a star complex already exists, the system will fail with a X'0A3' wait state with a X'84' reason code.
• If a down-level MVS system (at least an MVS/ESA SP 4.1.0 system, but not OS/390® release 2) is IPLed with one of the ring-related parameters (GRS=START, JOIN, or TRYJOIN), and a star complex already exists, the system will fail with a X'0A3' wait state with a X'84' reason code.
• If a down-level MVS system (prior to MVS/ESA SP 4.1.0) is IPLed with one of the ring-related parameters (START, JOIN, or TRYJOIN) and a star complex already exists, global resource serialization will not be able to detect this type of error. See Error scenarios you can avoid.
• If the installation is running a ring complex where all systems are interconnected using CTC support rather than XCF communication, and the operator or system programmer accidently specifies GRS=STAR when IPLing a system that should be part of the ring, global resource serialization will not be able to detect this type of error. See Error scenarios you can avoid.