Why BUFNO is used for output datasets

sravani · New User Joined: 17 Jul 2005 Posts: 2

Hi,

My JCL has the following statements. Can anyone tell me why BUFNO is used for output datasets?

//SORTOUT DD DSN=&&TEMP1,BUFNO=29,
// DISP=(NEW,PASS,DELETE),
// SPACE=(CYL,(1500,1000),RLSE,,ROUND),

Thanks,
Sravani

withnams · New User Joined: 06 Jul 2005 Posts: 26 Location: Chennai

It perhaps means the number of buffers alloacted for that dataset.

ironmike · New User Joined: 07 Aug 2005 Posts: 33

BUFNO= is the number of buffers that will be used for buffering output for that data set. The example you coded appears to be for a sequential file. Increasing the number of buffers can improve performance if QSAM is used for writing to an output sequential file. Your example is for a SORTOUT DD, so the program writing to the file may be the SORT; SORT probably used BSAM or EXCP to write to this file, in which case SORT is probably doing intelligent buffer management and the BUFNO=29 may be ignored; if your program and not the SORT is writing to the file out of a SORT exit (e.g., the SORT E35 exit), then your program may be using QSAM and bumping up BUFNO can speed up the output process.

Here's a quote from IBM's DFSMS Using Data Sets manual:

mmwife · Super Moderator Joined: 30 May 2003 Posts: 1592

DFSORT and Syncsort calculate and use their own BUFNO params for I/P and O/P.

Those supplied in the JCL are ignored.