Session Manager Control Entries

The Session Manager subkey contains the global variables used by the Session Manager. These values are stored under the following Registry path:

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HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager

CriticalSectionTimeout REG_DWORD

Specifies the deadlock time-out for critical sections. Usually, retail installations of Windows NT will not time-out and detect deadlocks.

Default: 0x278d00

GlobalFlag REG_DWORD

Controls various Windows NT internal operations. You can change this value to disable the OS/2 subsystem if you want to run bound applications in a VDM, rather than under the OS/2 subsystem. Set this value to 20100000 to disable the OS/2 subsystem.

Default: 0x21100000

Memory Management Control Entries

The Memory Management subkey defines paging options under the following Registry path:

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HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control
    \Session Manager\Memory Management

The paging file parameters should be defined by using the System icon in Control Panel and choosing the Virtual Memory button.

IoPageLockLimit REG_DWORD Number of bytes

Specifies the limit of the number of bytes that can be locked for I/O operations. When this value is 0, the system uses the default (512K). The maximum value is about the equivalent of physical memory minus pad, which is 7 MB for a small system and grows as the amount of memory grows. For a 64 MB system, pad is about 16 MB; for a 512 MB system, pad is about 64 MB.

Default: 512K

LargeSystemCache REG_DWORD Number

Specifies, for a nonzero value, that the system favor the system-cache working set rather than the processes working set. Set this value by choosing the Windows NT Advanced Server installation base.

Default: 0

NonPagedPoolSize REG_DWORD Number of bytes

Specifies the size of nonpaged pool in bytes. When this value is 0, the system uses the default size (based on physical memory). The maximum amount is about 80 percent of physical memory.

Default: 0

PagedPoolSize REG_DWORD 0 to 128 MB

Specifies the size of paged pool in bytes. When this value is 0, the system uses the default size (32 MB). See also the entry for RegistrySizeLimit at the beginning of this section.

Default: 0x3000000 (32 MB)

PagingFiles REG_MULTI_SZ System_Paging_Files

Specifies page file information set by choosing the System icon in Control Panel.

Default: C:\pagefile.sys 27

Subsystem Startup Control Entries

The following is the Registry path for the subsystem settings established at startup:

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HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet
    \Control\Session Manager\SubSystems

These values should only be maintained by the system. You should not need to manually define these settings.

Optional REG_MULTI_SZ Subsystem names

Defines subsystems that are only loaded when the user starts an application that requires this subsystem.

Default: Os2 Posix

SystemPages REG_DWORD Number of entries

Defines the number of system page table entries reserved for mapping I/O buffers and other information into the system address space. Each entry maps a single page. The value 0 indicates that the default number of entries is to be used.

Default: TBD