On Sat, 25 Aug 2012 08:49:49 -0700, Skip Robinson wrote:
>Zero space allocation is perfectly valid. As is SPACE (0,1) also. The
>result is just as requested. In either case, the data set exists in the
>VTOC but takes up no space on disk.
>
Ummm... no. By experiment, it allocates one track. There has to
be room for the count field. And SPACE=(65535,1) allocates
two tracks. This surprises me. Does 3390 support blocks spanning
tracks?
Also surprisingly, SPACE=(0,99999) allocates 8,334 tracks;
SPACE=(1,99999) allocates 1,163 tracks. Did I do something
wrong? Did someone divide by zero?
>The data set is treated as 'real',
>including GRS enqueue. Hence it can be used like any other exclusively
>held data set to serialize execution.
>
The data set's being 'real' has little to do with GRS enque. I can code:
//GRS EXEC PGM=WOMBAT,COND=(0,LE)
//SERIAL DD DISP=OLD,DSN=NONE.SUCH
The data set needn't exist; the step isn't executed; yet I believe
an exclusive ENQ is issued for its name which could be used to
serialize execution.
>From: Paul Gilmartin
>Date: 08/25/2012 08:27 AM
>
>The JCL RM says:
>
> blklgth -- (only if AVGREC is not coded)
> Specifies the average block length of the data, in bytes.
> The blklgth is a decimal number from 0 through 65535.
-- gil
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