<s>
The	O
Sort/Merge	O
utility	B-Application
is	O
a	O
mainframe	O
program	O
to	O
sort	O
records	O
in	O
a	O
file	O
into	O
a	O
specified	O
order	O
,	O
merge	O
pre-sorted	O
files	O
into	O
a	O
sorted	O
file	O
,	O
or	O
copy	O
selected	O
records	O
.	O
</s>
<s>
Internally	O
,	O
these	O
utilities	O
use	O
one	O
or	O
more	O
of	O
the	O
standard	O
sorting	B-Algorithm
algorithms	I-Algorithm
,	O
often	O
with	O
proprietary	O
fine-tuned	O
code	O
.	O
</s>
<s>
Because	O
of	O
this	O
,	O
unlike	O
more	O
recent	O
sort	O
programs	O
,	O
early	O
Sort/Merge	O
programs	O
placed	O
great	O
emphasis	O
on	O
efficient	O
techniques	O
for	O
sorting	B-Algorithm
data	O
on	O
secondary	O
storage	O
,	O
typically	O
tape	B-Architecture
or	O
disk	B-Application
.	O
</s>
<s>
Prior	O
to	O
the	O
System/370	B-Device
,	O
all	O
IBM	B-Device
mainframe	I-Device
operating	B-General_Concept
systems	I-General_Concept
included	O
sort/merge	O
utilities	O
.	O
</s>
<s>
With	O
the	O
announcement	O
of	O
virtual	B-Architecture
storage	I-Architecture
operating	B-General_Concept
systems	I-General_Concept
,	O
DOS/VS	B-Application
and	O
OS/VS	B-Application
,	O
IBM	O
unbundled	O
much	O
of	O
the	O
software	O
and	O
offered	O
chargeable	O
sort/merge	O
program	O
products	O
.	O
</s>
<s>
For	O
OS/VS	B-Application
IBM	O
offered	O
5740-SM1	O
,	O
OS/VS	B-Application
Sort/Merge	O
,	O
later	O
renamed	O
Data	O
Facility	O
Sort	O
(	O
DFSORT	B-Application
)	O
.	O
</s>
<s>
In	O
1990	O
IBM	O
introduced	O
a	O
new	O
merge	O
algorithm	O
called	O
BLOCKSET	O
in	O
DFSORT	B-Application
the	O
successor	O
to	O
OS/360	O
Sort/Merge	O
.	O
</s>
<s>
Indeed	O
,	O
most	O
Sort/Merge	O
applications	O
use	O
the	O
wide	O
range	O
of	O
additional	O
processing	O
capabilities	O
,	O
rather	O
than	O
purely	O
sorting	B-Algorithm
or	O
merging	O
records	O
:	O
the	O
Sort/Merge	O
product	O
is	O
a	O
very	O
fast	O
way	O
of	O
performing	O
input	O
to	O
and	O
output	O
from	O
these	O
functions	O
.	O
</s>
<s>
Quite	O
a	O
number	O
of	O
"	O
user	O
exits	O
"	O
are	O
supported	O
,	O
and	O
these	O
may	O
be	O
load	O
modules	O
(	O
i.e.	O
,	O
a	O
member	O
of	O
a	O
library	O
)	O
,	O
or	O
object	O
decks	O
(	O
i.e.	O
,	O
the	O
output	O
of	O
an	O
assembler	O
)	O
,	O
with	O
the	O
Sort/Merge	O
application	O
loading	O
(	O
load	O
modules	O
)	O
or	O
linking	O
(	O
object	O
decks	O
;	O
termed	O
"	O
dynamic	O
link	O
editing	O
"	O
in	O
DFSORT	B-Application
)	O
the	O
exit	O
,	O
as	O
specified	O
and	O
required	O
.	O
</s>
<s>
Working	O
storage	O
datasets	O
(	O
i.e.	O
,	O
SORTWK01	O
,	O
...	O
,	O
SORTWKnn	O
)	O
may	O
be	O
disk	B-Application
or	O
tape	B-Architecture
,	O
although	O
the	O
BLOCKSET	O
algorithm	O
is	O
restricted	O
to	O
disk	B-Application
working	O
storage	O
;	O
more	O
working	O
storage	O
datasets	O
generally	O
improves	O
performance	O
.	O
</s>
<s>
Sort/merge	O
is	O
important	O
enough	O
that	O
there	O
are	O
multiple	O
companies	O
each	O
selling	O
their	O
own	O
sort/merge	O
package	O
for	O
IBM	B-Device
mainframes	I-Device
and	O
their	O
z/OS	B-Application
,	O
z/VM	B-Application
and	O
z/VSE	B-Application
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
DFSORT	B-Application
sold	O
by	O
IBM	O
.	O
</s>
<s>
(	O
Some	O
of	O
these	O
companies	O
also	O
sell	O
versions	O
for	O
other	O
platforms	O
,	O
such	O
as	O
Unix	B-Application
,	O
Linux	B-Application
,	O
or	O
Windows	B-Application
.	O
)	O
</s>
<s>
When	O
migrating	O
from	O
the	O
mainframe	O
to	O
other	O
platforms	O
such	O
as	O
Unix	B-Application
,	O
Linux	B-Application
or	O
Windows	B-Application
,	O
a	O
Sort/Merge	O
utility	B-Application
is	O
needed	O
.	O
</s>
<s>
These	O
products	O
emulate	O
the	O
functions	O
of	O
DFSORT	B-Application
outside	O
of	O
the	O
Mainframe	O
environment	O
.	O
</s>
<s>
DFSORT	B-Application
is	O
often	O
referred	O
to	O
by	O
its	O
program	O
name	O
,	O
ICEMAN	O
(	O
component	O
ICE	O
;	O
the	O
original	O
OS/360	O
Sort/Merge	O
program	O
name	O
was	O
IERRCO00	O
,	O
component	O
IER	O
,	O
also	O
with	O
"	O
alias	O
"	O
SORT	O
)	O
.	O
</s>
<s>
Balanced	O
(	O
BALN	O
)	O
-	O
required	O
a	O
minimum	O
of	O
12,000	O
bytes	O
of	O
main	O
storage	O
and	O
2x+1	O
tape	B-Architecture
devices	O
for	O
intermediate	O
storage	O
,	O
where	O
x	O
is	O
the	O
number	O
of	O
input	O
tape	B-Architecture
volumes	O
,	O
up	O
to	O
a	O
maximum	O
of	O
15	O
input	O
reels	O
.	O
</s>
<s>
Polyphase	O
(	O
POLY	O
)	O
-	O
required	O
a	O
minimum	O
of	O
12,000	O
bytes	O
and	O
3	O
intermediate	O
storage	B-Architecture
tape	I-Architecture
devices	O
.	O
</s>
<s>
Oscillating	O
(	O
OSCL	O
)	O
-	O
required	O
21,000	O
bytes	O
and	O
max( x+2	O
,	O
4	O
)	O
intermediate	O
tape	B-Architecture
devices	O
,	O
where	O
x	O
is	O
the	O
number	O
of	O
input	O
volumes	O
,	O
up	O
to	O
a	O
maximum	O
of	O
15	O
.	O
</s>
<s>
Balanced	O
(	O
BALN	O
)	O
-	O
required	O
a	O
minimum	O
of	O
13,000	O
bytes	O
and	O
3	O
to	O
6	O
disk	B-Application
work	O
areas	O
.	O
</s>
<s>
Crisscross	O
(	O
CRCX	O
)	O
-	O
Not	O
available	O
for	O
IBM	B-Device
2311	I-Device
or	O
IBM	O
2301	O
auxiliary	O
storage	O
devices	O
.	O
</s>
<s>
The	O
distribution	O
techniques	O
listed	O
for	O
tape	B-Architecture
sorts	O
were	O
retained	O
by	O
the	O
OS/VS	B-Application
SORT	O
program	O
,	O
now	O
called	O
"	O
conventional	O
techniques.	O
"	O
</s>
<s>
The	O
disk	B-Application
sort	O
techniques	O
were	O
replaced	O
by	O
four	O
new	O
ones	O
:	O
</s>
