IBM 3270 Manual page 248

Appendix I. 3274 Control Storage -Requirements
The following paragraphs describe how to determine the control storage
requirements for the selected model of the 3274 Control Unit.
Models lA, lC, lD, and 51C
After having selected the configuration support and the desired special
features for your 3274, you will have to determine the control storage
required. Because some combinations of functions and features exceed the
basic storage capacity of the control unit you have chosen, you may have to
order Extended Function Store features to provide adequate control
storage. Still other combinations may exceed the maximum control storage
possible with all Extended Function Store features. Such combinations are
invalid configurations. In these situations, you must forfeit feature(s) in
order to reduce the control storage requirements to an amount not
exceeding the maximum control storage possible.
Do the follmving procedural steps to determine which, if any, Extended
Function Store features must be ordered for the model you have selected:
1.
Select the Configuration Support option that contains the functions you
want.
2. Refer to the appropriate figure of control storage requirements, and
select the features and functions you want.
a. Use Figure I-1 for a 3274 Model lA.
b. Use Figure I-2 for a 3274 Model lC using SNA protocol.
c. Use Figure I-3 for a 3274 Model lC using BSC protocol.
d. Use Figure I-4 for a 3274 Model lD.
e. Use Figure I-5 for a 3274 Model 51C using SNA protocol.
f.
Use Figure I-6 for a 3274 Model 51C using BSC protocol.
3. Determine the total Type C and total Type D storage required for the
features and functions you selected in step 2.
4. Add the Type C and Type D totals to determine the total control storage
required. If this total is less than or equal to 65,536, no Extended
Function Store features are required and you can stop here. If the total
is greater than 65,536, continue with step 5.
5. For Model lA, lC, or lD, see Figure I-7. If you chose Configuration
Support A or B, begin at Line 1 and work down. If you chose
Configuration Support C, begin at Line 4 and work down. Stop at the
first line that satisfies the control storage requirements you determined
Appendix I. 3274 Control Storage Requirements
I-1