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8.47.3 Parameter

msize

The value of msize must be a valid decimal number. The actual upper limit is dete-
rmined by the host system's architecture, the operating system and on some sys-
tems the amount of physical memory and paging space that is available.

For storage sizes less than 16M, sizes not on a 4K boundary are rounded up to the
next 4K boundary. Otherwise, storage sizes not on a 1M boundary are rounded up
to the next 1M boundary.

The minimum size is 4K for architecture levels ALS0 and ALS1 (S/370 and
ESA/390), and 8K for architecture level ALS2 (ESAME) and higher. A maximum of
64M may be specified for architecture level ALS0 (S/370), 2048M (2G) for ALS1
(ESA/390) and 16E for architecture level ALS2 (ESAME) and higher.

The default on startup is 2M.

xsize

The value of xsize must be a valid decimal number. The actual upper limit is deter-
mined by the host system’s architecture, the operating system and on some sys-
tems the amount of physical memory and paging space that is available.

Storage sizes not on a 1M boundary are rounded up to the next 1M boundary. The
lower limit and default is 0.

B

‘B’ determines that the number given is specified in bytes (no multiplier). Specifying
the storage in bytes is possible only for main storage.

K

‘K’ determines that the number given is specified in kilobytes (multiplier 2**10).
Specifying the storage in kilobytes is possible only for main storage.

M

‘M’ determines that the number given is specified in megabytes (multiplier 2**20).
This is the default if no unit is appended.

G

‘G’ determines that the number given is specified in gigabytes (multiplier 2**30).

T

‘T’ determines that the number given is specified in terabytes (multiplier 2**40). On
32-bit machines the unit terabytes is not available.

P

‘P’ determines that the number given is specified in petabytes (multiplier 2**50).
Specifying the storage in petabytes is possible only for main storage. On 32-bit
machines the unit petabytes is not available.

E

‘E’ determines that the number given is specified in exabytes (multiplier 2**60).
Specifying the storage in exabytes is possible only for main storage. On 32-bit
machines the unit exabytes is not available.

LOCK

Attempt to lock the storage (pages locked by the host operating system).

UNLOCK

Leave the store unlocked (no pages locked by the host operating system, pageable
by host OS). This is the default.

Notes:

The actual upper limit is determined by the host system’s architecture and operating system and the
amount of physical memory and available paging space. The total of MAINSIZE and XPNDSIZE on host
systems with a 32-bit architecture will be limited to 4G; host systems with a 64-bit architecture will be
limited to less than 16E.

Using minimum storage sizes, storage sizes less than or not on a 64K boundary for architecture level
ALS0 (S/370) or not on a 1M boundary for architecture level ALS1 (ESA/390) and higher, it may be pos-
sible to generate error conditions not covered by the “Principles of Operations”.

Use of storage sizes greater than supported by the guest operating system may generate incorrect re-
sults or error conditions within the guest operating system.

8.47.4 Overview Storage Allocation Units

Unit

Multiplier

Name (Symbol)

IEC Name (IEC Symbol)

Restrictions

B

None

Byte (B)

Byte (B)

Main storage only

K

2**10

Kilobyte (kB)

Kibibyte (KiB)

Main storage only

M

2**20

Megabyte (MB)

Mebibyte (MiB)

G

2**30

Gigabyte (GB)

Gibibyte (GiB)

T

2**40

Terabyte (TB)

Tebibyte (TiB)

Not on 32-bit machines

P

2**50

Petabyte (PB)

Pebibyte (PiB)

Not on 32-bit machines

E

2*60

Exabyte (EB)

Exbibyte (EiB)

Not on 32-bit machines

Table 19: Storage Allocation Units