Your PL/I application can create workstation VSAM data sets, or it can access VSAM data sets created by other programs. When you open a file to be associated with a workstation VSAM data set, and that data set does not exist, PL/I creates it using the attributes and options you specify in the DECLARE statement or in a DD:ddname environment variable.
When your application accesses an existing VSAM data set, PL/I determines its type—sequential, direct, or keyed.
The operation of writing the initial data into a newly-created VSAM data set is referred to as loading in this publication.
Use each of the access methods, DDM|ISAM|BTRIEVE, to access data sets that were created with that particular access method. For example, you cannot use the ISAM access method to access data sets you created with the BTRIEVE access method.