Benefits of Configuring More Memory in the IBM z/OS Software StackSignificant performance benefits can be realized by increasing the amount of memory that is assigned to various functions in the IBM® z/OS® software stack, operating system, and middleware products. IBM DB2® and IBM MQ buffer pools, dump services, and large page usage are just a few of the functions whose ease of use and performance can be improved when more memory is made available to them.
Although the magnitude of these improvements can vary widely based on several factors, including potential I/Os to be eliminated, resource contention, workload, configuration, and tuning, clients must carefully consider whether their environment can benefit from the addition of memory to the software functions that are described in this IBM RedpaperTM publication. This paper describes the performance implications of increasing memory in the following areas:
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64-bit storage a z/OS amount of memory applications cache Chapter CICS address space CICS regions Cognos Dynamic Cubes Controller memory dump coupling facility CPU cost DASD data set I/O data sharing DB2 buffer pools DB2 for z/OS delay DFSORT I/O elapsed environment group buffer pools IBM Redbooks IBM z/OS IBM z13 improved increased InfoSphere International Business Machines ISPF Java heaps JVMs large pages LPAR memory dump capture memory object messages MQ buffer pools MQ for z/OS OMEGAMON option output pageset performance benefits Poughkeepsie queue manager real memory real storage reduce I/O RELEASE(DEALLOCATE RMF Monitor SAN Volume Controller send and receive service class shown in Figure simulated pool sort sync I/O synchronous I/Os TCP receive buffer TCP send thread reuse throughput trademarks transactions tuning virtual storage Volume Controller memory VSAM WebSphere MQ workload z/OS Communications Server