Hercules V4.00.0 - User Reference Guide - HEUR040000-00 Page 166 (166 of 661)

Example 2:

Set the size of the expanded storage to 2 GB. Lock the memory into the storage.

XPNDSIZE 2048 LOCK

or

XPNDSIZE 2G LOCK

5.81 YROFFSET (TOD clock offset from actual date)

5.81.1 Function

Specifies the number of years the TOD clock is offset from the actual date. Positive numbers will move
the clock forward in time while negative numbers will move it backward. A common value for non-Y2K-
compliant operating systems is YROFFSET -28 which has the advantage that the day of the week and
the presence or absence of February 29 is the same as the current year.

5.81.2 Syntax

Descriptive

+years -years

Diagram

+ years ¬¬¬§¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬ÊÍ

-years

5.81.3 Parameter

+years

Specifies the number of years the TOD clock is offset positive from the actual date.
This value may not be specified as greater than +/-142 years, the total range of the
TOD clock. Specifying a value that causes the computed TOD clock year to be
more than 142 years later than SYSEPOCH will produce unexpected results.

-years

Specifies the number of years the TOD clock is offset positive from the actual date.
This value may not be specified as greater than +/-142 years, the total range of the
TOD clock. Specifying a value that causes the computed TOD clock year to be
earlier than the value of SYSEPOCH will produce unexpected results.

5.81.4 Examples

Example 1:

Specify 28 years to offset the TOD clock from the actual date.

YROFFSET -28

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Extracted Text (may have errors)

Example 2:

Set the size of the expanded storage to 2 GB. Lock the memory into the storage.

XPNDSIZE 2048 LOCK

or

XPNDSIZE 2G LOCK

5.81 YROFFSET (TOD clock offset from actual date)

5.81.1 Function

Specifies the number of years the TOD clock is offset from the actual date. Positive numbers will move
the clock forward in time while negative numbers will move it backward. A common value for non-Y2K-
compliant operating systems is YROFFSET -28 which has the advantage that the day of the week and
the presence or absence of February 29 is the same as the current year.

5.81.2 Syntax

Descriptive

+years -years

Diagram

+ years ¬¬¬§¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬ÊÍ

-years

5.81.3 Parameter

+years

Specifies the number of years the TOD clock is offset positive from the actual date.
This value may not be specified as greater than +/-142 years, the total range of the
TOD clock. Specifying a value that causes the computed TOD clock year to be
more than 142 years later than SYSEPOCH will produce unexpected results.

-years

Specifies the number of years the TOD clock is offset positive from the actual date.
This value may not be specified as greater than +/-142 years, the total range of the
TOD clock. Specifying a value that causes the computed TOD clock year to be
earlier than the value of SYSEPOCH will produce unexpected results.

5.81.4 Examples

Example 1:

Specify 28 years to offset the TOD clock from the actual date.

YROFFSET -28

Help

5.80 XPNDSIZE (Expanded storage size)

5.80.1 Function

XPNDSIZE specifies the expanded storage size. Storage is allocated in megabytes, unless a specific unit
is specified. The actual upper limit of the expanded storage is determined by the host system's architec-
ture, operating system, and on some systems the amount of physical memory and paging space you
have available. The lower limit is 0.

The practical limit depends on the maximum amount of storage that can be obtained by “malloc” (usually
around 1 GB on 32-bit platforms; on 64-bit platforms the value should only be limited by available paging
space).

An additional optional argument determines the locking state of the allocated memory (page lock by host
operating system). The LOCKED option indicates that the memory is to be locked into storage while UN-
LOCKED (the default) indicates that the memory is not locked into the storage.

Please note that Hercules preserves the last locking state of XPNDSIZE. Once storage is locked, any
subsequent change to the expanded storage size will honor the existing lock state of memory unless the
lock state is specified again on the XPNDSIZE command.

Caution: Do not lock expanded storage unless sufficient real memory is available to back up the request.
Failure to do so may require the host system to be rebooted.

5.80.2 Syntax

Descriptive

xsize[ ] [

Diagram

~¬¬¬ ¬¬¬®
~¬¬¬ CK ¬¬¬®

ÊÊ¬¬¬ ¬¬
xsize ¬¬¦¬¬¬¬¬¬¬¬¬¦¬¬¬¦¬¬¬¬¬¬¬¬¬¬¬¬¬¬¦¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬ÊÍ

¬¬¬«
LOCK

¬¬¬
T ¬¬¬

5.80.3 Parameter

size

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.

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.

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). This is
the default.

Notes:

The actual upper limit is determined by the host system’s architecture and operating system, the guest
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 less
than 4G; host systems with a 64-bit architecture will be limited to less than 16E.

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

5.80.4 Overview Storage Allocation Units

Unit

Multiplier

Name (Symbol)

IEC Name (IEC Symbol)

Restrictions

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

Table 7: Storage Allocation Units

5.80.5 Examples

Example 1:

Set the size of the expanded storage to 256 MB. Do not lock the memory into the storage.

XPNDSIZE 256

or

XPNDSIZE 256M

or

XPNDSIZE 256 UNLOCK

or

XPNDSIZE 256M UNLOCK

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5.82 Process and Thread Priorities

This section covers details regarding the priority settings within Hercules. The relevant system parame-
ters are:

CPUPRIO DEVPRIO HERCPRIO SRVPRIO TODPRIO

5.82.1 Process Priorities

Under Linux a process is a thread and thread priority information applies instead.

For Windows the following conversions are used for translating Unix process priorities to Windows priority
classes:

Unix
Process Priority

Windows
Priority Class

Meaning

-20 to -16

Realtime

Process that has the highest possible priority. The threads of
the process preempt the threads of all other processes, inclu-
ding operating system processes performing important tasks.
For example, a real-time process that executes for more than a
very brief interval can cause disk caches not to flush or cause
the mouse to be unresponsive.

-15 to -9

High

Process that performs time-critical tasks that must be executed
immediately. The threads of the process preempt the threads of
normal or idle priority class processes. An example is the Task
List, which must respond quickly when called by the user, re-
gardless of the load on the operating system. Use extreme care
when using the high-priority class, because a high-priority class
application can use nearly all available CPU time.

-8 to -1

Above Normal

Process that has priority above the Normal class but below the
High class.

0 to 7

Normal

Process with no special scheduling needs.

8 to 15

Below Normal

Process that has priority above the Idle class but below the
Normal class.

16 to 20

Low

Process whose threads run only when the system is idle. The
threads of the process are preempted by the threads of any
process running in a higher priority class. An example is a
screen saver. The idle-priority class is inherited by child pro-
cesses.

Table 8: Process Priority Conversions

Caution: On Windows, the value you choose for your process priority has a direct impact on how your
thread priorities are interpreted! You should never modify one without understanding what impact you are
doing so might have on the other!

5.82.2 Thread Priorities

On Linux/Unix hosts Hercules needs to be a setuid root program to allow it to reset its dispatching priority
to a high (negative) value (i.e. “chown root.root hercules; chmod +s hercules”).

For Windows the following conversions are used for translating Linux/Unix thread priorities to Windows
thread priorities:

Unix
Thread Priority

Windows
Thread Priority

Meaning

-20 to -16

Time Critical

Base priority of 15 for Idle, Below Normal, Normal, Above Normal,
or High class processes, and a base priority of 31 for Realtime
class processes.

-15 to -9

Highest

Priority 2 points above the priority class.

-8 to -1

Above Normal

Priority 1 point above the priority class.

0 to 7

Normal

Normal priority for the priority class.

8 to 15

Below Normal

Priority 1 point below the priority class.

16 to 19

Lowest

Priority 2 points below the priority class.

20

Idle

Base priority of 1 for Idle, Below Normal, Normal, Above Normal,
or High class processes, and a base priority of 16 for Realtime
class processes.

Table 9: Thread Priority Conversions

Caution: On Windows, your Thread Priority is interpreted differently based on your chosen Process Prio-
rity setting! You should never modify your Thread Priority settings without first reviewing your chosen Pro-
cess Priority setting!

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5.81 YROFFSET (TOD clock offset from actual date)

5.81.1 Function

5.81.2 Syntax

5.81.3 Parameter

5.81.4 Examples

Extracted Text (may have errors)

5.81 YROFFSET (TOD clock offset from actual date)

5.81.1 Function

5.81.2 Syntax

5.81.3 Parameter

5.81.4 Examples

Help

loading

5.80 XPNDSIZE (Expanded storage size)

5.80.1 Function

5.80.2 Syntax

5.80.3 Parameter

5.80.4 Overview Storage Allocation Units

5.80.5 Examples

5.82 Process and Thread Priorities

5.82.1 Process Priorities

5.82.2 Thread Priorities