SHOWCAT—Display the catalog

The information shown here is provided for compatibility only.

The SHOWCAT (show, or display, the catalog) macro enables you to retrieve information from a catalog independently of an open data set defined in the catalog.

The SHOWCAT macro has three forms: standard, list, and execute. Although the integrated catalog facility catalog have different structures, the SHOWCAT macro supports integrated catalog facility catalogs. Thus, all references to catalogs in this discussion of the SHOWCAT macro apply to integrated catalog facility catalogs.

You can use the IGGSHWPL macro to generate a DSECT statement and labels for the fields in the parameter list for SHOWCAT.

The entries in a catalog are interrelated. More than one entry is required to describe an object and its associated objects; one entry points to one or more other entries, which point to yet others. Figure 1 shows the interrelationship among entries that describe the following types of objects:

Alternate index (G)
Cluster (C)
Data component (D)
Index component (I)
Path (R)
Upgrade set (Y)

For example, an alternate-index entry points to the entries of its data and index components, its base cluster, and its path. SHOWCAT enables you to follow the arrows in Figure 1. You first issue SHOWCAT on the name of an object.

Figure 1. Interrelationship Among Catalog Entries. An arrow indicates a pointer from one entry to another.

The image shows a cluster (C) that points to the entries of its data component (D) and its index component (I) , and to an alternate index (G). The data and index components also point to the cluster. The alternate index (G) points to the entries of its data component and its index component, and to the cluster. The cluster's data component points to the upgrade set (Y), which in turn points to the data component and index component of the alternate index. A path (R) points to the data and index components of the cluster. Another path points to the data and index components of both the cluster and the alternate index.

The information VSAM returns to you includes the control interval numbers of catalog records in entries describing associated objects. You then issue SHOWCAT on a control interval number to retrieve information from one of these other entries.

The first time you issue SHOWCAT, VSAM searches catalogs in the following order to locate the entry that describes the object you name:

The master catalog.
When the object has a qualified name, the catalog, if any, whose name or alias is the same as the first-level qualifier of the object's name.

VSAM returns the address of the access method control block that defines the catalog. In subsequent use of SHOWCAT, you can specify that address, which causes VSAM to search only that catalog.

SHOWCAT should not be used for z/OS UNIX files as z/OS UNIX files are not reflected in the catalogs. Specifying the pathname in the NAME parameter is not valid and returns unpredictable results.

SHOWCAT is valid in AMODE(24) and AMODE(31). For AMODE(31) callers the address of the parameter list that is passed may be above the line.