The lower the number of concurrent transactions in the system, the lower the usage of virtual storage. Therefore, improving transaction internal response time decreases virtual storage usage. Keeping programs in storage above the 16MB line, and minimizing physical I/Os makes the largest contribution to well-designed transaction internal response time improvement.
Item | Topic |
---|---|
CICS® region | |
Increase CICS region size | Increasing the CICS region size |
Reorganize program layout within region | Defining programs as resident, nonresident, or transient |
Split the CICS region | Splitting online systems: virtual storage |
DSA sizes | |
Specify optimal size of the dynamic storage areas upper limits (DSALIM, EDSALIM) | The dynamic storage areas |
Adjust maximum tasks (MXT) | Setting the maximum task specification (MXT) |
Control certain tasks by transaction class | Using transaction classes (MAXACTIVE) to control transactions |
Put application programs above 16MB line | Putting application programs above the 16MB line |
Database considerations | |
Increase use of DBCTL and reduce use of shared database facility | Setting DBCTL minimum threads (MINTHRD) |
Replace DL/I function shipping with IMS™ DBCTL facility | Setting DBCTL minimum threads (MINTHRD) |
Review use of DB2® threads and buffers | Tuning the CICS DB2 attachment facility: Introduction |
Applications | |
Use PL/I shared library facility | Using the PL/I shared library |
Journaling | |
Increase activity keypoint frequency (AKPFREQ) value | Setting the activity keypoint frequency (AKPFREQ) |
Terminals, VTAM® and SNA | |
Reduce VTAM input message size | Setting the size of receive-any input areas (RAMAX) |
Reduce concurrent VTAM inputs | Setting the size of the receive-any pool (RAPOOL) |
Reduce terminal scan delay | Adjusting the terminal scan delay (ICVTSD) |
Discourage use of MSGINTEG and PROTECT | Adjusting the number of transmissions in SNA transaction flows (MSGINTEG, and ONEWTE) |
Reduce concurrent VTAM logon/logoffs | Limiting the number of concurrent logon/logoff requests (OPNDLIM) |
Reduce AIQMAX setting for autoinstall | Tuning automatic installation of terminals |
MRO/ISC considerations | |
Implement MVS™ cross-memory services with MRO | CICS intercommunication facilities and performance: overview |
Implement MVS cross-memory services with shared database programs | CICS intercommunication facilities and performance: overview |
SSL (Secure Sockets Layer) | |
Increase CICS region size | Managing the performance of Secure Sockets Layer support |
JVMs | |
Tune the JVM initialization options | Java applications using a Java virtual machine (JVM): improving performance |
Miscellaneous | |
Reduce use of aligned maps | Choosing aligned or unaligned maps |
Prioritize transactions | Prioritizing tasks |
Use only required CICS recovery facilities | CICS recovery: performance considerations |
Recycle job initiators with each CICS startup | Using job initiators |