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TYPE=J
specifies
that,
for
each
data
control
block
referred to, the
programmer has supplied a job file control block (JFCB) to be
used
during
initialization.
A
JFCB
is an internal representation of
information in a DD control statement.
During initialization of a data control block, its associated
JFCB
may
be modified with information from the data control block or an
existing data set label or with system control information.
The system always creates a job file
control
block
for
control
statement.
The job file control block is placed
queue on direct-access storage.
Its position, in relation
JFCBs created for the same job step, is noted
in
a
main
table.
'
each
DD
in a job
to other
storage
When
this
operand
is
specified,
the user must also supply a DD
control statement.
However, the amount of information
g~ven
in the
DD statement is at the
programmer's
discretion,
because
he
can
ignore
the
system-created
jot
file
control
block.
(See
the
examples of
the
RDJFCB
macro-instruction
for
a
technique
for
modification of a systen-created JFCB.)
Note:
The DD statement must specify at least:
• Device allocation.
• A ddname corresponding to the associated data control block DCBDDNAM
field.
RDJFCB -- Read a Job File Control Block (S)
The
RDJFCB
macro-instruction causes a job file control block (JFCB)
to be read from the job queue into roain storage for
each
data
control
block specified.
r----------T----------T------------------------------------------------,
I
Nawe
I
Operation
I
Operand
I
~----------+-~--------+------------------------------------------------i
I
[syml:olJ
I
RDJFCB
I
({dcb-addr, [(opt :l-code[,opt
2
-code])],} •.• )
I
L __________
~
__________
~
________________________________________________ J
dcb, (opt:l
I
opt
2 )
(same as deb, Opt:ll and Opt2 operands in OPEN macro-instruction)
Although
the
opt:l and opt2 operands are not meaningful during the
execution of
the
RDJFCB
macro-instruction,
these
oper~nds
can
appear in the L-form of either the RDJFCB or OPEN macro-instruction
to
generate
identical
parameter
lists, which can be referred to
with the E-forw of either macro-instruction.
Examples:
The macro-instruction in EX1 creates a parameter list for two
data control blocks: INVEN and MA'STER.
In creating the list, both
data
control
blocks are assumed to be opened for input; opt2 for both blocks
is
assumed
to
be
DISP.
The
macro-instruction
in
EX2
reads
the
system-created
JFCBs
for rUVEN and MASTER frcm the job queue into main
~torage,
thus making the JFCB's available to
the
problem
program
for
mooification.
The macro-instruction in EX3 modifies the parameter list
entry for the data control block namEd INVEN and indicates, through
the
TYPE=J operand, -that the problem is supplying the JFCB's for system use.
System Macro-Instructions
131
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