An attempt is made to read the DD or member of the DD (whichever is specified). This request is resolved if the read is successful.
If you are exporting symbols, the prelinker creates a definition side-deck. After the prelinker processes all its input, it puts the prelinked output object module into SYSMOD. If a definition side-deck was generated, it is put into SYSDEFSD and is a sequential data set or a PDS member. The linking process then begins when the linkage editor takes its primary input from SYSLIN, which refers to the prelinked object module data set.
The IBM-supplied cataloged procedures and REXX EXECs for C/C++ use the DLL versions of the IBM-supplied class libraries by default; the IBM-supplied class libraries definition side-deck data set, SCLBSID, is included in the SYSIN concatenation.
Figure 1 shows an overview of the basic prelinking process.