Input/output contention performance checklist

Note:

Ideally, I/O contention should be reduced by using very large data buffers and keeping programs in storage. This would require adequate central and expanded storage, and programs that can be loaded above the 16MB line

Item Topic
VSAM considerations
Review use of LLA Using LLA (MVS library lookaside)
Implement Hiperspace™ buffers Using VSAM local shared resources (LSR)
Review/increase data set buffer allocations within LSR Defining VSAM buffer allocations for NSR (INDEXBUFFERS and DATABUFFERS)
Use data tables when appropriate Using data tables to improve performance
   
Database considerations
Replace DL/I function shipping with IMS/ESA® DBCTL facility Setting DBCTL minimum threads (MINTHRD)
Reduce/replace shared database access to online data sets Setting DBCTL minimum threads (MINTHRD)
Review DB2® threads and buffers Tuning the CICS DB2 attachment facility: Introduction
   
Journaling
Increase activity keypoint frequency (AKPFREQ) value Setting the activity keypoint frequency (AKPFREQ)
   
Terminals, VTAM® and SNA.
Implement terminal output compression exit Compressing output terminal data streams
Increase concurrent VTAM inputs Setting the size of the receive-any pool (RAPOOL)
Increase concurrent VTAM logon/logoffs Limiting the number of concurrent logon/logoff requests (OPNDLIM)
Minimize SNA terminal data flows Adjusting the number of transmissions in SNA transaction flows (MSGINTEG, and ONEWTE)
Reduce SNA chaining Using SNA chaining to segment large messages (TYPETERM RECEIVESIZE, BUILDCHAIN, and SENDSIZE)
   
Miscellaneous
Reduce DFHRPL library contention Defining programs as resident, nonresident, or transient
Review temporary storage strings Tuning the use of CICS temporary storage (TS)
Review transient data strings Optimizing the performance of the CICS transient data (TD) facility

Related tasks
Performance checklists
Virtual storage above and below 16MB line performance checklist
Real storage performance checklist
Processor cycles performance checklist
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