CA Dynam for VSE User Guide

Hierarchy of File Information
Hierarchy of File Information
Initially, CA Dynam/FI uses the program DTF information. If the Catalog is
present, values defined there override the program DTF information.
Finally, CA Dynam/FI values defined on the DLBL or TLBL statement override
both the program DTF and the Catalog information. For input files, the device
type is determined either by the type of label (DLBL or TLBL) or by the device
type indicated in the Catalog record created for the file, if there is one.
Unit Record Simulation
Unit record simulation allows you the flexibility of routing any unit record
device (card reader, printer, card punch) as a tape, sequential disk or VSAM
file.
Unit record simulation lets you temporarily assign a system file to disk. This
eliminates potential errors caused when a job abends and permanently
assigned system files are not released. Furthermore, blocksize can be
optimized, reducing I/O.
The degree of support for unit record simulation is controlled by parameters in
the DYNAM/FI option record. For more information about setting DYNAM/FI
parameters, see the Programming Guide. Alternatively, you can set or change
support for unit record simulation with the SET statement.
Since DTFCD and DTFPR contain no file name (DTF name), CA Dynam/FI
generates a file name based on the logical unit name specified. The file name
'FISYSxx' is used, where 'xx' is derived from the logical unit specification in the
user program DTF. This logical unit may be overridden using JCL or the CA
Dynam Catalog, but the original logical unit specification is used when deriving
the file name.
For example, if a user program specifies SYS004 as the logical unit for printed
output, the following JCL would change that printer DTF to a disk DTF.
// DLBL FISYS04,'PRINT.OUTPUT.DISK.DATA',7,SD
// EXTENT SYS004,3350WK,1,0,19,50
// ASSGN SYS004,DISK,VOL=3350WK,SHR
Notice that the logical unit (SYS004) is appended to the special name FISYS in
order to derive a DTF name that matches with the label information.
Of course CA Dynam/FI parameters may be used to change the SYS number,
set a more efficient block size or make any other desired changes as required.
6–4 User Guide