Local checks run in the IBM® Health Checker for z/OS® address space, hzsproc. You can write local checks in either Metal C or assembler. See Writing local and remote checks in Metal C.

Because the local check runs in the IBM Health Checker address space, writing a local check is simpler than a remote check, but the data you can access might be a little more limited than you can access from a remote check running in the caller's address space. Make sure that your check can access the data it needs from the IBM Health Checker for z/OS address space and that it does not require any potentially disruptive actions, such as I/O intensive operations, serialization, or waits. This is important because if your check hangs in the hzsproc address space, it can affect the performance of IBM Health Checker for z/OS and all the other checks.

Local checks must be APF authorized.

The following figure shows the parts of a local check. The shaded items show the parts that a check developer must provide:

Figure 1. The parts of a local check