ABCs of z/OS System Programming Volume 3 - IBM Redbooks

3.26 IGDSMSxx member BreakPointValue
BreakPointValue (0- 65520) in cylinders
Value used by SMS in making volume selection
decisions and subsequently by DADSM
If the allocation request is less than the BreakPointValue,
the system prefers to satisfy the request from free space
available from the track-managed space
If the allocation request is equal to or higher than the
BreakPointValue, the system prefers to satisfy the
request from free space available from the
cylinder-managed space
Figure 3-28 BreakPointValue parameter
SETSMS BreakPointValue(0-65520)
If the preferred area cannot satisfy the request, both
areas become eligible to satisfy the requested space
Using the BreakPointValue
How the system determines which managed space is to be used is based on the derived
BreakPointValue for the target volume of the allocation. EAV volumes are preferred over
non-EAV volumes where space >=BreakPointValue (there is no EAV volume preference
where space < BreakPointValue).
BreakPointValue (0- 65520)
BreakPointValue (0- 65520) is used by SMS in making volume selection decisions and
subsequently by DADSM. If the allocation request is less than the BreakPointValue, the
system prefers to satisfy the request from free space available from the track-managed
space.
If the allocation request is equal to or higher than the BreakPointValue, the system prefers to
satisfy the request from free space available from the cylinder-managed space. If the
preferred area cannot satisfy the request, both areas become eligible to satisfy the requested
space amount.
Note: The BreakPointValue is only used to direct placement on an expanded address
volume.
Chapter 3. Extended access volumes 95