The exit must build the key field every time it is called,
regardless of whether the call is to process the control record or
a record in the HLL_ITEM table. It also has to consider that it may
be invoked several times in the same call.
This is described in FBE for a key or AIX field.
Several other points should be noted:
- No data verification is performed in the exit. It assumes that
all field values are correct.
- The three fields in the control record table that are reengineered
are typical examples of reengineering fields.
- A different technique is used for each reengineered field to demonstrate
that there are different ways to reengineer a field.
- Note the use of EXRET. When the exit is processing a request for
the control record, EXRET is set to Y to prevent CICS VT from processing the fields that are
mapped to the HLL_ITEM table.
There are more efficient ways to code this program but a key
objective is to make it easy to understand.