Allocating optional ISPF table libraries

The data set described in Table 1 is optional. You must allocate it only if an application uses table services.

Table 1. Table Data Sets
DDNAME	Description	RECFM	LRECL	BLKSIZE
ISPTABL	Table Output Library	FB	80	(See note)

Note: The block size must be a multiple of 80. You can specify BLKSIZE=0 to use a system determined block size.

The table output library must be a partitioned data set. The ISPTABL ddname that defines the table output library can specify the same data set as the table input library, ddname ISPTLIB. The first data set in the ISPTLIB concatenation should be the same as the data set used for ISPTABL. This ensures predictable behavior of dialogs that use table services without specifying the LIBRARY keyword. The output and input data sets must be the same if the updated version of a table is to be reprocessed by the same dialog that updated it.

You must allocate the table output library to ddname ISPTABL before using table services. ISPF includes ENQ logic to prevent simultaneous updates. ISPTABL must not specify a concatenated sequence of data sets. It is possible to have the dialog dynamically allocate ISPTABL and free it upon completion. However, in an environment in which multiple dialogs can be executing, it is more practical to permanently allocate ISPTABL. ISPTABL should be allocated with DISP=SHR, even though it specifies an output data set. An application can use the ISPTABL allocation if it already exists or use a LIBDEF for ISPTABL so that only this application is affected.

For more information about table locking and allocation, see the "Protecting Table Resources" topic in z/OS ISPF Dialog Developer's Guide and Reference.