Save Record Positions During Sequential Access
Learn how to save record positions during sequential access in Datacom VSAM Transparency.
In native VSAM, string numbers are assigned to RPLs while requests are processed. If the request requires
remembering
the current position to process the next request, the string number is maintained, otherwise it is released.In the VSAM Interface Table, you specify a value for the parameter
STRNO=
. If you do not code STRNO=
, the Transparency uses as the default the value specified in the current file's ACB at execution time. Datacom VSAM Transparency
uses strings and string number specifications in a manner analogous to native VSAM.Let us consider a file defined in the VSAM Interface Table with a string number greater than one and GETIT=YES. When doing read-only sequential processing, the Transparency uses the string number value to determine the number of
Datacom/DB
Request Areas it needs. In Datacom/DB
, only one GSETL/GETIT Request Area per table may be active within a program at one time. The Transparency permits GETIT processing of a file using multiple strings by allowing only one string at a time to operate in GETIT mode. Once GETIT processing begins on a string, that string operates in GETIT mode until the end of sequential access is reached. Then the Transparency releases blocked GETIT resources from that string and allocates them to another string on which sequential access is being performed without benefit of GETITs. If more than one active string meets this criteria, blocked GETIT resources are allocated on a first come first serve basis.