The major resources used or managed by CICS® consist of the following:
Contention at lower levels prevents full use of higher-level resources. To avoid or reduce resource contention, you can:
Two sets of symptoms and solutions are provided in this section. The first set provides suggested solutions for poor response (see Solutions for poor response time), and the second set provides suggested solutions for a variety of resource contention problems (see Symptoms and solutions for particular resource contention problems).
Table 10 shows four levels of response time, in decreasing order of severity. The major causes are shown for each level together with a range of suggested solutions. Your first step is to check the causes by following the advice given in Assessing the performance of your system. When you have identified the precise causes, the relevant checklist in Performance checklists tells you what solutions are available and where to find information in Part 4 of this book on how to implement the solutions.
Major Causes | Overall Solution |
---|---|
Level 1: Poor response at all loads for all transactions | |
High level of paging | Reduce working set, or allocate more real storage |
Very high usage of major resources | Reconsider system resource requirements and redesign system
Check for application errors and resource contention |
Level 2: Poor response at medium and high loads | |
High level of paging | Reduce working set, or allocate more real storage |
High processor usage | Reduce pathlength, or increase processor power |
High DB or data set usage | Reorganize data sets, or reduce data transfer, or increase capacity |
High communication network usage | Reduce data transfer, or increase capacity |
TP or I/O access-method constraint | Increase buffer availability |
CICS limit values exceeded | Change operands, or provide more resources, or check if errors in application |
Level 3: Poor response for certain transactions only | |
Identify common characteristics | As for level 2 |
Lines or terminal usage | Increase capacity, or reduce data transfer, or change transaction logic |
Data set usage | Change data set placement buffer allocations or change enqueue logic or data set design |
High storage usage | Redesign or tune applications |
Same subprograms used by transactions | Redesign or tune application subprograms |
Same access method or CICS features used by transactions | Reallocate resource or change application. Reevaluate use of feature in question |
Limit conditions | Reallocate resource or change application |
Level 4: Poor response for certain terminals | |
Check network loading as appropriate | Increase capacity of that part of network |
Check operator techniques | Revise terminal procedures |
Check CEDA terminal definitions | Redefine CEDA terminal definitions |
This section presents a general range of solutions for each type of constraint. You should:
See DASD tuning for suggested solutions.
See the Virtual storage above and below 16MB line performance checklist for a detailed list of suggested solutions.
See the Real storage performance checklist for a detailed list of suggested solutions.
See the Processor cycles performance checklist for a detailed list of suggested solutions.