5. OPERATION › 5.1 Operation Overview › 5.1.3 VSAM/ICF Catalog Scan Overview › 5.1.3.3 VCCVVSAM--VSAM Catalog Scan

5.1.3.3 VCCVVSAM--VSAM Catalog Scan

The VCCVVSAM module scans old style (pre-ICF) VSAM master and
user catalogs, formats the VCC SMF record, and calls the
VCCWRITR module, which processes the records for the
VCCDATA/SMF file.  A more detailed description of the
VCCVVSAM functions follows:

    o  Old style VSAM catalogs are split into two parts:  a
       high-key range and a low-key range.  The high-key
       range contains a true name record for each data set
       present in the catalog.  The true name records are
       read sequentially to obtain the addresses of the
       active detail records, which reside in the low-key
       range area.  It sorts the addresses into physical
       record sequence to minimize the DASD arm movements
       within the low-key range area.  VCCVVSAM selects the
       following records from the low-key range for
       processing:

         C - catalog record type that describes VSAM
             data set clusters.

         D - catalog record type that describes the data
             component of VSAM data sets.

         I - catalog record type that describes the index
             component of a VSAM data set.

         G - catalog record type that describes alternate
             indexes.

         E - catalog extension records for the above record
             types.

         U - catalog record type that describes user
             catalogs.  When it encounters a user catalog in
             the master catalog scan, VCCVVSAM determines if
             the user catalog is excluded or included through
             the use of the INCLUDECAT or EXCLUDECAT
             parameters.  If it is excluded, the record is
             ignored.  If it is included, then a test is made
             to make sure that the device on which it resides
             is known to VCC (see Chapter 3, VCC Usage, for
             further information on defining DASD devices to
             VCC).  If these tests are passed, then VCCVVSAM
             will call a VCCVSCAN routine to add the user
             catalog entry to the Catalog Name Queue (CNQ)
             for subsequent processing.

    o  VCCVVSAM records all data contained in these catalog
       records.  Note that this also includes the catalog
       self-defining records at the front of the catalog.  It
       does not record catalog recovery area information.