When a
data
set
name
is:
specif
ied,
the
96-byte
data
portion
of
the
format
1 DSCB,
and
the
absolute
track
address
of
the
DSCB
are
read
into
main
storage.
When
the
absolute
track
address
cf
a
DSCB
is
specified,
the
44-byte
key
portion
and
the
96-byte
data
portion
of
the
DSCB
are
read
into
main
storage.
Example:
In
the
following
example,
the
format
1
DSCB
for
data
set
A.B.C
is
read
into
main
storage.
The
serial
nurrber
of
the
volume
containing
the
DSCB
is
770655.
r---------T-----·-----T-------------------------------------------------,
I Name I
Operation
I
Operand
I
~---------+----------+-------~-----------------------------------------i
I I OBTAIN I
DSCBABC
READ
DSCB
FOR
DATA
I
I I
Check
Exceptional
Returns
SET
A.B.C
INTO
MAINI
I
DSCBABC
I
CAMLST
I
SEARCH,DSABC,VOLNUM,WORKAREA
STORAGE
AREA
NAMED
I
I
DSABC
I
DC
I
CL44'A.B.C'
WORKAREA.
96-BYTE I
I
VOLNUM
I
DC
I
CL6'770655'
DATA
PORTION
IS
I
I
WORKAREAI
DS
I
OD
READ.
THE
REST
OF
I
I I
DS
I 350C
THE
AREA
IS
USED
BYI
I I I
THE
OBTAIN ROUTINE I
L
_________
~
__________
~
_________________________________________________
J
The
OBTAIN
macro-instruction
points
to
the
CAMLST
macro-instruction.
SEARCH,
the
first
operand
of
CAMLST,
specifies
that
a
DSCB
be
read
into
main
storage.
DSABC,
the
second
operap.d~
specifies
the
main
storage
location
of
a
44-byte
area
into
which
you
have
placed
the
fully
qualified
name
of
the
data
set
whose
associated
DSCB
is
to
be
read.
VOLNUM,
the
third
operand,
specifies
the
main
storage
location
of
a
6-byte
area
into
which
you
have
placed
the
serial
nurrber
of
the
volume
containing
the
required
DSCB.
WORKAREA,
the
fourth
operand,
specifies
the
main
storage
location
of
a
350-byte
work
area
that
is
to
contain
the
DSCB~
After
execution
of
these
macro-instructions,
the
first
96
b~tes
of
the
work
area
contain
the
data
portion
of
the
fornat
1 DSCB;
the
next
five
bytes
contain
the
absolute
track
address
of
the
DSCB.
The
OBTAIN
routine
uses
the
rest
of
tht
area
as
a
~ork
area.
HOW
TO
DELETE
A
DATA
SET
You
delete
a
data
set
stored
on
direct-access
volumes
by
using
the
SCRATCH
and
CAMLSTmacro-instructions.
This
caUSES
all
data
set
control
blocks
<DSCB)
for
the
data
set
to
be
deleted,
and
all
space
occupied
by
the
data
set
to
be
made
available
for
reallocation.
If
the
data
set
to
be
deleted
is
sharing
a
split
cylinder,
the
space
will
not
be
made
available
for
reallocation
until
all
data
sets
on
the
split
cylinder
are·
deleted.
A
data
set
cannot
be
deleted
if
the
expiration
date
in
the
fermat
1
DSCB
has
not
passed,
unless
you
choose
to
ignore
the
expiration
date.
You
can
ignore
the
Expiration
date
by
using
the
OVRD
option
in
the
CAMLST
macro-instruction.
If
a
data
set
to
be
deleted
is
stored
on
more
than
one
volume,
either
a
device
must
be
available
on
which
to
mount
the
volumes,
or
at
least
one
volume
must
be
mounted.
In
addition,
all
other
required
volu~es
must
l:e
serially
mountable.
Certain
volumes,
such
as
the
system
residence
volume,
must
always
be
mounted.
When
deleting
a
data
set,
you
must
tuild
a
complete
volume
list
in
main
storage.
This
volume
list
consists
of
volurre
pointers
for
all
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
Maintaining
the
Catalog
and
the
Volurre
Table
of
contents
19
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