Data set has a 123-extent limit. |
Data set has a 16-extent limit. |
Directory is expandable and indexed
by member name; faster to search directory. |
Fixed size directory is searched
sequentially. |
PDSEs are device independent: records
are reblockable and the TTR is simulated as a system key. |
For PDSs, TTR addressing and block
sizes are device dependent. |
Uses
dynamic space allocation and automatically reclaims space. Using
IEBCOPY or DFSMSdss COPY to copy all members of a PDSE creates a larger
index than copying members one at a time.
Recommendation: Allocate
a PDSE with secondary space to permit the dynamic variation in the
size of the PDSE index.
|
Must use IEBCOPY compress to reclaim
space. |
You can create multiple members at
the same time. |
You can create one member at a time. |
PDSEs contain either program objects or data
members but not both. z/OS MVS Program Management: User's Guide and Reference describes
the advantage of program objects over load modules. |
Whereas PDSs contain data members or load modules
but there is no attempt to keep data members and load modules from
being created in the same PDS. |
Replacing a member without replacing
all of its aliases causes the alias entries to be deleted. |
Replacing a member without replacing
all of its aliases causes the alias entries to be abandoned. They
are "orphans" and eventually might point to the wrong member. |
Alias names for program objects, in a PDSE,
can be up to 1024 bytes long. To access these names, you must use
the DESERV interfaces. Primary names for program objects are restricted
to 8 bytes. |
All names for PDS members must be 8 bytes long. |
Support generations for members,
with version 2 PDSEs. |
Do not support generations for
members. |
An S002-89 abend occurs when attempting
to read a member of a PDSE that is RACF EXECUTE protected. This is
not allowed even if the user is in supervisor state. |
An S016-08 abend occurs when attempting
to read a member of a PDS that is RACF EXECUTE protected but the user
is not in supervisor state. |
The "fast data access" function of
the program management binder should be used to read a program object
from a PDSE. This will convert the program object to a documented
format. |
BPAM, BSAM, or QSAM may be used to
read a load module from a PDS. |