IBM Tivoli NetView for z/OS Programming: Pipes - IBM notice

PIPE QSAM
198 Programming: Pipes
of the same PDS. When this situation occurs, the QSAM stage issues message
DSI084I and a return code of 16. In this case, the system issues the message
"IEC143I 213-30".
v If you omit the FILE operand, a unique ddname with a name of SYSnnnn is
assigned by dynamic allocation and then returned in the CNM272I message. Do
not specify the FILE operand unless a specific ddname must be allocated. This
prevents allocations failing because of ddname conflicts. It also prevents problems
caused by deallocating a data set that is shared by multiple NetView tasks. Each
NetView task must allocate the file with a unique ddname. If one task deallocates
its ddname, the other tasks do not lose their access to the file.
v If you allocate a partitioned data set as an input data set and specify a member
name that does not exist, the ALLOCATE command completes successfully with
a return code of 0. However, you receive an OPEN error when you attempt to
open the data set for input.
v Allocate the files with the FREE operand whenever possible. The files are then
deallocated automatically when they are closed. This reduces virtual storage use.
There is also an MVS limit of 1635 concurrent allocations. When this limit is
reached, deallocate resources to do additional allocations. Allocating files with
the FREE operand helps to keep the allocations below the limit. This procedure
also minimizes the time that critical data sets, volumes, and units are tied up.
System output data sets also are spooled immediately when the files are closed,
instead of when the NetView program ends.
v If you specify the same operand more than once on the ALLOCATE command,
the last one specified is used and the previous operands are ignored.
v The NetView LISTA command displays the ddnames and dsnames of currently
allocated files.
v For disk files, the following operands are ignored by dynamic allocation:
COPIES HOLD | NOHOLD
DEN OUTLIM
DEST POSITION
FORMS WRITER
v For tape files, the following operands are ignored by dynamic allocation:
BLOCK | TRACK | CYLINDERS KEYLEN
CONTIG | MXIG | ALX MSVGP
COPIES OUTLIM
DEST RELEASE
DIR ROUND
FORMS SPACE
HOLD | NOHOLD WRITER
v The QSAM stage uses one or more QSAM read or write operations. The
NetView program uses the QSAM GET macro to perform read operations and
the QSAM PUT macro to perform write operations. See the appropriate QSAM
documentation for more information about the QSAM GET and the QSAM PUT.
If the NetView program is running under z/OS Version 1.10 or earlier, and if a
QSAM read operation is performed on a newly allocated data set that is not
managed by SMS before any write, the read operation might return residual data
from the previously deleted data set. If this previously deleted data set had a
different record size, the QSAM read operation fails with message