Previous topic |
Next topic |
Contents |
Contact z/OS |
Library |
PDF
Migration to version 2 buffers z/OS MVS Program Management: Advanced Facilities SA23-1392-00 |
|
Support for multiple text classes and a logical module structure in which sections are subdivided into classes requires some fundamental changes in the ESD. (See Understanding binder programming concepts for a better understanding of module structure and content). At the highest level in the ESD hierarchy is the Section Definition (SD entry), which assigns some attributes to the section. At the next level is the Element Definition (ED entry), one for each class requested in the section. ED records are new and need not be present for binder-defined, nontext classes, such as ESD and IDR. Elements can contain either labels (LD entries) or parts (PR entries), depending upon the binding method for the class. Beginning with PM2, LD entries are required for all entry points: An SD entry is no longer an implied entry into offset zero of that section. Two PM1 data classes have been extended in PM2 in order to properly reflect the multipart program object. Class B_ESD has been extensively modified, with some data moving from the SD record to lower level records, such as the ED and LD. In addition, new data fields have been added to support future expansion. Class B_RLD has also been modified for multipart modules, although not as extensively as the ESD. These changes must be considered when converting your program from version 1 buffers and API calls to version 2. If your program was designed for version 1 buffers, you may not need to migrate to version 2 (or a later version) if you are processing data only from traditional (load module compatible) modules. However if a PM2 (or later level) program object exploits new function, it might contain data that cannot be converted to version 1 buffer format. In this case, you will receive an error message. In addition, the binder fast data API supports only PM1 format program objects with version 1 buffers. If you want to convert your program to use the version 2 buffer
formats and API calls, you must consider the following:
The following tables show the correspondence between data elements
in the two versions of the ESD and RLD buffers. Format codes shown
have the following meaning:
New data elements are normally set to zero when processing a PM1 module. This is not true if the new value is determined from other data present in the record. |
Copyright IBM Corporation 1990, 2014
|