This key contains parameters that control system startup, such as subsystems to load, the size and location of paging files, and so on.
The Control subkey itself can contain the following value entries:
RegistrySizeLimit REG_DWORD 4 bytes to unlimited
Limits both the amount of paged pool the Registry may use, and the amount of disk space.
If the value of RegistrySizeLimit is less than 4 megabytes, it will be forced up to 4 megabytes. If it is greater than about 80% of the size of PagedPoolSize, it will be set down to 80% of the size of PagedPoolSize. (It is assumed that PagedPoolSize will always be bigger than 5 megabytes.)
RegistrySizeLimit sets a maximum, not an allocation, meaning a large RegistrySizeLimit value will be used only if it is actually needed by the Registry. It does not guarantee that much space will be available for use in the Registry.
Setting RegistrySizeLimit to 0xffffffff will effectively set it to be as large as PagedPoolSize allows (80% of PagedPoolSize). PagedPoolSize can be set to a maximum of 128 megabytes, thus limiting RegistrySizeLimit to 102 megabytes.
Default: 8 MB (That is, 25 percent of the default PagedPoolSize.)