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Using the ALLOCATE Command
Controlling the Block Size of Concatenated Data Sets
You can control the block size used to process concatenated data sets by using the
BLKSIZE operand to specify one block size for all of the concatenated data sets.
Example
To concatenate data sets T1.DATA, T2.DATA, and T3.DATA within ddname
INDATA with block size 8000 for each data set, enter:
ALLOCATE FILE(indata) DATASET(t1.data,t2.data,t3.data) +
BLKSIZE(8ððð) SHR REUSE
When you omit the BLKSIZE operand from the concatenation statement, the block
size of the first data set is used for all the data sets. Suppose data sets created
with the following block sizes were concatenated as shown in the following
example:
T1.DATA
T2.DATA
T3.DATA
BLKSIZE(32ðð)
BLKSIZE(8ððð)
BLKSIZE(8ðð)
Example
ALLOCATE FILE(indata) DATASET(t1.data,t2.data,t3.data) SHR REUSE
The block size of the first data set (3200) is used as the block size for all the data
sets. When the first data set's block size is smaller than another data set's block
size in the concatenation, an error results. In the above example, T2.DATA's 8000
block size is truncated, because T1.DATA's smaller block size of 3200 was
specified first.
If you do not use the BLKSIZE operand, be sure the first data set in the
concatenation has a block size as large or larger than those of the data sets that
follow.
For more information about operands to use while concatenating data sets, see the
ALLOCATE command in OS/390 TSO/E Command Reference.
Using Your Terminal To Provide Input to a Program
When you are running a program in the foreground, you can use your terminal to
provide input to the program by issuing the ALLOCATE command and substituting
an asterisk (*) for a data set name.
To use your terminal to provide input to a program that specifies ddname SYSIN as
an input data set, enter:
Example
ALLOCATE FILE(sysin) DATASET(\)
The way to indicate the end of input depends on the program. For example, some
programs require that you type /\ and others require that you type end.
Chapter 4. Allocating Data Sets
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