The node error table

To understand the sample NEP, first look at the node error table structure in more detail.

Node error table is often abbreviated to NET. You should not confuse this acronym with “net” (as in “network”), or with a NETNAME.

You can generate a node error table using the CICS® macro DFHSNET. See Node error table and DFHSNET—generating the node error table. You choose how complex this table is to be.

The node error table must be defined as a RESIDENT program. This makes it easy for the NEP to find it (using a CICS LOAD request), and ensures that any counters are not reset by reloading. You can give the table any name you like. The default is DFHNET.

The table consists of sets of error-recording areas. Each set is called a node error block (NEB) and is used to count node errors relating to a single LU. You can dedicate specific NEBs to specific LUs throughout a CICS run; and you can leave other, reusable NEBs for general use. If you expect to accumulate error statistics about 10 LUs concurrently, you need 10–12 NEBs.

Each NEB may contain multiple recording areas, one being used for each group of errors you want to distinguish. The error groups correspond to those in the NEP. That is, they are groups of error types requiring separate processing logic.

Each recording area is known as an error status block (ESB). You specify the space reserved for each ESB, and it typically includes space to count the errors, or record when the first of the present series occurred. Note that in any one NEB the counting is for one LU only.

Finally, you can specify a threshold count and a time limit in the table. These are constants that can be used by code in the NEP to test an ESB, to see if a given type of error has occurred more than the threshold number of times in the stated interval. The time limit also affects the interval between using a general NEB for one LU and then reusing it for another.

A minimal NET would consist of a handful of NEBs, each with just one ESB, grouping together all types of error that are of interest.