LINK (Link to the CXX)

LINK (Link to the CXX)

When a data area or index area is initialized, it is linked to the Directory (CXX) used in the INIT AREA=CXX function. The link is done using the CXX name. An edit when the data set is opened during all other processing helps ensure that the CXX and data set are linked. If the CXX and data set are found not to be linked, an error is produced.

The LINK function provides protection for all functions except INIT against JCL errors, for example, pointing to the production database instead of the test database. Therefore use extra caution to help ensure that the CXX in use and the data area or index area are correct when submitting an INIT. Of course the edit works when every CXX has a unique CXX name, which we recommend as a best practice. You can run the DBUTLTY REPORT MEMORY=MVS to obtain a list of MUFs on the local LPAR that JOB runs on. This report helps to identify any MUFs that have non-unique CXX names.

When you execute the LINK function, each area in the database is processed in the following sequence:

1. The Index Area (IXX)
2. Other index areas
3. Data areas

Each area is processed as follows:

• The area data set name from the Directory (CXX) is accessed.
• If the data set name is not blanks, the area is opened.
• If the open is successful, the control block of the area is read.
• If the CXX name is found not to be current, it is updated and written.