iX V6.5 (30391-90011)

646 AppendixD

Multiple Calls to DBLOCK

Sort Sequence for Lock Descriptors

If it is absolutely necessary to make multiple DBLOCK calls, the following information about

how TurboIMAGE/XL performs locking may be useful.

Sort Sequence for Lock Descriptors

TurboIMAGE/XL internally sorts the lock descriptors in the order as follows:

• Ascending data set number

• Lower bound of data item value for each data set number

If a lock descriptor's relative operator (relop) ﬁeld contains <=, it collates before any other

lock descriptors for the data set because it has the lowest possible lower bound for its

value. For example, a lock descriptor of SALES:QUANTITY <= 10 collates before a lock

descriptor of SALES:QUANTITY = 5, because the lower bound of the former is the lowest

possible integer for an I-type data item.