CA Dynam for VSE User Guide

Tape File Management Utilities
Using the ASSGN Statement
The // ASSGN statement has two formats:
[//] ASSGN SYSnnn[,DUMMY]
or
// ASSGN SYSxxx,SYSyyy
Format One
The first format is shown below.
[//] ASSGN SYS001[,DUMMY]
This format makes the specified logical unit assignment to a dummy device.
The logical unit assignment must be correctly made before opening the file,
because some programs, such as CA SORT, can use either tape or disk
devices. A dummy ASSGN satisfies this requirement, allowing AVR to be used
at OPEN time. The default dummy devices are 7F0 through 7FF, but can be
altered by changing the DYNAM/T option record. TDYNASN uses as many of
these devices as are necessary. The dummy devices are in device-down
(DVCDN) status and ownership bits are not set on. This prevents job control
from ever trying to use such a device.
Each dummy ASSGN statement generates an assignment to a different dummy
device unless an UPSI 01 statement is present. In this case, all ASSGNs are
made to the same device.
You can normally use UPSI 01 to assign all LUBS to the same dummy PUB.
However, this is not permitted with the MERGE and TP functions of CA SORT.
They verify that all input files are assigned to different devices.
Never use the // ASSGN SYSxxx,DUMMY format of TDYNASN for any program
that does I/O on a tape file without opening it (such as DITTO).
Examples:
Assume DUMMY(7F0,7FF) set up in DYNAM/T option record
// EXEC TDYNASN
// ASSGN SYS001,DUMMY (would be assigned to 7F0)
// ASSGN SYS002,DUMMY (would be assigned to 7F1)
// ASSGN SYS003,DUMMY (would be assigned to 7F2)
/*
// UPSI 01 (make all assigns to same dummy device)
// EXEC TDYNASN
// ASSGN SYS001,DUMMY (would be assigned to 7F0)
// ASSGN SYS002,DUMMY (would be assigned to 7F0)
// ASSGN SYS003,DUMMY (would be assigned to 7F0)
/*
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