<s>
An	O
Input/Output	B-Application
Supervisor	I-Application
Block	I-Application
(	O
IOSB	B-Application
)	O
is	O
a	O
data	B-General_Concept
structure	I-General_Concept
employed	O
exclusively	O
by	O
the	O
Start	B-Application
Input/Output	I-Application
interface	O
of	O
MVS/370	O
and	O
successor	O
IBM	B-Device
mainframe	I-Device
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
The	O
IOSB	B-Application
describes	O
the	O
I/O	O
request	O
and	O
passes	O
parameters	O
to	O
and	O
receives	O
responses	O
from	O
the	O
Input/Output	B-Application
Supervisor	I-Application
(	O
IOS	O
)	O
.	O
</s>
<s>
An	O
IOSB	B-Application
is	O
always	O
paired	O
with	O
a	O
Service	B-Application
Request	I-Application
Block	I-Application
(	O
SRB	O
)	O
.	O
</s>
