Sysview DCKEYS command shows a table can have multiple keys as expected with different lengths. However in DCTABLES DETAIL for a table, the "Key Length" field is different and larger than any of the individual key lengths. For example for AGR it is 1080:
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DBID Area Table TableID Records Occurrence
2 DD1 AGR 17 347 AGGREGATE
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Attributes Key Information Status Current History
Logging YES Change Master YES Constraint Error NO NO
Pipeline YES Dup Master YES Fwd Rcvry Pnd NO NO
Recovery YES Cluster Key ID 0 Load Pending NO NO
Compression YES Cluster Key Len 0 Related Pend NO NO
Forced Off NO
Miscellaneous Encryption
Record Length 809 Compress Exit Type NONE
Table Referred NO Encryption Key Method NONE
Table Referring NO DL/I T Constraint NO
Key Length 1080 Domain Constraint NO
Refs In Base NO Definition Posted
Table Loaded YES Index Loaded YES
Table Constraint NO Restricted
MoveToPart
Release : 16.0
Component : SYSVIEW
The value that Sysview displays as 'Key Length' comes from the Datacom CXX. It is the same as the Datacom CXX report value:
LENGTH OF KEY/ELEMENTS - 1,080
Amount of storage needed by the MUF to hold the CXX control blocks that contain each key, element, or special field definitions for the given table.
See Datacom documentation on CXX REPORT