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volumes
on
which
the
data set is stored.
The first two bytes of the
list indicate the number of volume pointers that follow.
Each
12-byte
volume
pointer consists of a 4-byte device code, a 6-byte volume serial
number, and a 2-byte data set sequence number.
The sequence
number
is
always
zero
for direct-access volumes.
(Device codes are contained in
Appendix B of this chapter.)
Volumes are processed in the order they appear in
the
volume
list.
Those
volumes
that
are
pointed
to
at the beginning of the list are
processed first.
If a volume is not mounted, a message is issued to the
operator requesting him to mount the volume.
You can indicate
the
I/O
device
on which unmounted volumes are to be mounted by loading register
o
with the address of the UCB associated with the
device
to
be
used.
When
the
volume
is mounted, processing continues.
If you do not load
register 0 with a UCB address, its contents must be zero.
If the operator cannot mount the requested volume, he issues a
reply
indicating that he cannot fulfill the request.
A condition cede is then
set
in
the last byte of the volume pointer for the unavailable volume,
and the next volume
indicated
in
the
volume
list
is
processed
or
requested.
Example:
In
the
following
example, data set A .. B.C is renamed D.E.F.
The data set extends across two volumes.
r---------T----------T-------------------------------------------------,
I
Name
I
Operation
I
Operand
I
~---------+----------+-------------------------------------------------~
DSABC
OLDNAME
NEW NAME
VOLIST
SR
I
0,0
SET REG 0 TO ZEROI
RENAME
I
DSABC
CHANGE DATA SET
I
Check Exceptional Returns
NAME A.B.C. TO
I
CAMLST
I
RENAME,OLDNAI'<1E,NEWNAME, VOLIST
D.E.F
I
DC
I
CL44'A.B.C'
I
DC
I
CL44'D.E.F'
I
DC
I
H' 2'
TWO VOLUI"1ES
I
DC
I
X'30002001'
2311 DISK STORAGE
I
DC
I
CL6' 000017'
VOLUME SERIAL NO. I
DC
I
H'O'
SEQUENCE NUMBER
I
DC
I
X'30002001'
2311 DISK STORAGE I
DC
I
CL6' 000018'
VOLUME SERIAL NO.
I
. DC
I
H' 0 '
SEQUENCE NUMBER
I
_________
~
__________
~
_________________________________________________ J
The RENAME macro-instruction points to the CAMLST
macro-instruction.
RENAME,
the
first
operand
of
CAMLST,
specifies
that a data set be
renamed.
OLDNAME,
the
second
operand,
specifies
the
main
storage
location
of
a
44-byte
area
into
which
you
have
placed the fully
qualified name of the data
set
to
be
renamed.
NEWNAME,
the
third
operand,
specifies
the
main
storage
locaticn of a 44-byte area into
which you have placed the new name of the data set.
VOLIST, the
fourth
operand, specifies the main storage location of the voluule list you have
built.
Maintaining the Catalog and the Volume Table of Contents
21
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