CICS® VT
supports multiple access control blocks (ACBs) from the same program. For
example, multiple EXEC CICS STARTBR commands can be issued
for the same file by the same program. Similarly, a batch program can use
multiple request parameter lists (RPLs) for the same ACB. The
value you specify for the number of concurrent threads option defines the
maximum number of RPLs within all open ACBs that can be used for this data
set. For each concurrent thread, the size of the DDM driver module increases,
so only specify a value greater than 1 when necessary.
If a program tries to open an ACB and the DIM cannot support another concurrent thread, an abend occurs. This results in a transaction abend code 3105 for a CICS program. A batch program terminates with a U3105 abend code.