5 percent of available system memory when the first ISM segment is created
0 to 50 percent of physical memory
None. Values that are too small can cause the system to hang or performance to severely degrade when memory is consumed with ISM segments.
On database servers with large amounts of physical memory using ISM, the value of this parameter can be decreased. If ISM segments are not used, this parameter has no effect. A maximum value of 128 MB (0x4000) is almost certainly sufficient on large memory machines.