Was so ein falsch gesetzter Pointer alles bewirken kann...

Nun, es funktioniert - herzlichen Dank an Ronald und Baldur.

Für diejenigen die eine "all in one" Lösung für das QZLSLSTI API brauchen, habe ich dieses in Free RPG angefügt. Input = Pfad, Rückgabe = Share Name.

PHP-Code:
        ctl-opt DftActGrp(*no) Option(*NoDebugIO : *NoExpDDS : *SrcStmt);
 
      // Retrieve NetServer share informations
      // API: QZLSLSTI - ZLSL0100
      // ------------------------------------------------------------------------
 
          dcl-pi *n;
            inPath          char(50) options(*varsize) const;
            outShare        char(12);
          end-pi;
 
      // PROTOTYPES
      // ------------------------------------------------------------------------
 
      // Prototype for CrtUsrSpc procedure  (Create User Space)
       dcl-pr CrtUsrSpc extpgm('QUSCRTUS');
         *n                 like(SpaceName) const;                      // Name
         *n                 like(SpaceExtA) const;                      // Attribute
         *n                 like(SpaceSize) const;                      // Initial size
         *n                 like(SpaceInit) const;                      // Initial value
         *n                 like(SpaceAut)  const;                      // Authority
         *n                 like(SpaceText) const;                      // Text
         *n                 like(SpaceRepl) const options(*nopass);     // Replace existing
         *n                 like(DS_Error)  options(*nopass);           // Error feedback
         *n                 like(SpaceDom)  options(*nopass);           // Error feedback
       end-pr;
 
      // Prototype for GetUsrSpcP procedure (Get User Space Pointer)
       dcl-pr GetUsrSpc extpgm('QUSPTRUS');
         *n                 char(20) const;
         *n                 pointer ;
         *n                 like(QUSEC)options(*nopass);
       end-pr;
 
      // Prototype for GetUsrSpcP procedure (Get User Space Pointer)
       dcl-pr GetUsrSpcP pointer;
         *n                 char(20) const;
       end-pr;
 
      // Prototype for GetNumEnt procedure (Get Number of Entries in the User Space)
       dcl-pr GetNumEnt bindec(9);
         *n         char(20) const;
       end-pr;
 
      // Prototype for GetSpcEnt procedure (Get Specific Entry in the User Space)
       dcl-pr GetSpcEnt char(32767);
         *n         char(20) const;
         *n         bindec(9) value;
       end-pr;
 
      // Prototype for DltUsrSpc procedure  (Delete User Space)
       dcl-pr DltUsrSpc extpgm('QUSDLTUS');
         *n         char(20) const;
         *n         char(32767) options(*varsize);                      // Error feedback
       end-pr;
 
      // Prototype API QZLSLSTI
       dcl-pr QZLSLSTI extpgm ;
         *n         like(SpaceName) const;
         *n         like(LstFormat) const;
         *n         like(InfoQ) const;
         *n         like(I_O_Err) const;
       end-pr ;
 
      // Prototype for StringConvert procedure  (Convert String upper/lower)
       dcl-pr StringConvert varchar(65535);
         *n         varchar(65535) const;
         *n         bindec(9) value;                                    // Modus 0=up/1=low
       end-pr;
 
      // DECLARATIONS
      // ------------------------------------------------------------------------
       /copy qsysinc/qrpglesrc,qusec
       /copy qsysinc/qrpglesrc,qusgen
 
       dcl-s Error          char(32767);                                // Error feedback
       dcl-s NbrEntries     int(10);
       dcl-s Count          int(10);
       dcl-s iPath          varchar(65535);
       dcl-s uPath          varchar(65535);
       dcl-s Pos            int(5);
 
      // API User-Space Fields
       dcl-s SpaceName      char(20)   inz('@USRSPACE QTEMP     ');     // User Space
       dcl-s SpaceExtA      char(10)   inz('SHARE');                    // User Space Prod
       dcl-s SpaceSize      bindec(9)  inz(2048);                       // Initial Value
       dcl-s SpaceInit      char(1)    inz(x'00');                      // Space Init
       dcl-s SpaceAut       char(10)   inz('*ALL');                     // API Format
       dcl-s SpaceText      char(50)   inz('Check Shares IFS');         // User Space IFS
       dcl-s SpaceRepl      char(10)   inz('*YES');                     // Replace Space
       dcl-s SpaceDom       char(10)   inz('*USER');                    // Domain
 
      // API ZLSLSTI Fields
       dcl-s LstFormat      char(8)    inz('ZLSL0100');                 // API Format
       dcl-s InfoQ          char(15)   inz('*ALL');                     // API Format
       dcl-s I_O_Err        pointer;
 
      // API ErrorStructure
       dcl-ds DS_Error;
          Bytpv             bindec(4)  Pos(1)  inz(100);
          Bytav             bindec(4)  Pos(5)  inz(0);
          MsgId             char(7)    Pos(9);
          Resvd             char(1)    Pos(16);
          Exdta             char(240)  Pos(17);
          Exdta52           char(51)   overlay(Exdta);
       end-ds;
 
      // API DataStructure
       dcl-ds Share;
          Length            bindec(4)  Pos(1);
          ShareName         char(12)   Pos(5);
          DevType           bindec(4)  Pos(17);
          Permiss           bindec(4)  Pos(21);
          MaxUsr            bindec(4)  Pos(25);
          CurUsr            bindec(4)  Pos(29);
          SplFType          bindec(4)  Pos(33);
          OfsOfPathNam      bindec(4)  Pos(37);
          LenOfPathNam      bindec(4)  Pos(41);
          QuaOutQ           char(20)   Pos(45);
          PrtDrvTyp         char(50)   Pos(65);
          Text              char(50)   Pos(115);
          PathName          char(1024) Pos(165);
       end-ds;
 
      // PROCESSING
      // ------------------------------------------------------------------------
 
      // upper cases for inPath
        iPath = StringConvert(inPath : 0);                              // convert inPath upper
 
      // Create User-Space
        SpaceName = SpaceName;
        SpaceExtA = SpaceExtA;
        CrtUsrSpc (SpaceName : SpaceExtA : SpaceSize : SpaceInit : SpaceAut
                   : SpaceText : SpaceRepl : DS_Error  : SpaceDom);
 
      // Retrieve Net-Shares ZLSL0100
        QZLSLSTI   (SpaceName : LstFormat : InfoQ : I_O_Err);
        NbrEntries = GetNumEnt(SpaceName);
 
      // Transfer SpaceName to API structure ZLSL0100
        For Count = 1 to NbrEntries;
          Share  =  GetSpcEnt(SpaceName : Count);
          // Get Share Name
          clear uPath;
          uPath = StringConvert(PathName : 0);
          Pos = %scan(iPath : uPath);
          if Pos > 0;
            outShare = ShareName;
          endif;
        EndFor;
 
      // Delete SpaceName
        DltUsrSpc(SpaceName:Error);
        *InLr = *On;
 
 
      // internal PROCEDURES
      // ------------------------------------------------------------------------
 
      // Procedure Name:  GetNumEnt
      // --------------------------
        dcl-proc GetNumEnt export;
          dcl-pi *n bindec(9:0);
            UsrSpcName            like(SpaceName) const;
          end-pi;
 
      // Local Variables
          dcl-s UsrSpcPntr        pointer;
          dcl-s Bigfield          char(32767) based(UsrSpcPntr);
 
      // Get the pointer for the user space
          GetUsrSpc(UsrSpcName : UsrSpcPntr);              // Move the based on pointer to
          QUSH0100 = BigField;                             // Return number of list entries
 
          return QUSNBRLE;
        end-proc;
 
 
      // Procedure Name:  GetUsrSpcP
      // ---------------------------
        dcl-proc GetUsrSpcP export;
          dcl-pi *n pointer;
            UsrSpcName            like(SpaceName) const;
          end-pi;
 
      // Local Variables
          dcl-s SpacePoint        pointer;
 
      // Set error code structure to use basic feedback
          QUSBPRV = 16;
 
      // Get the pointer for the user space
          GetUsrSpc(UsrSpcName : SpacePoint : QUSEC);      // Move the based on pointer to
 
          return SpacePoint;
        end-proc;
 
 
      // Procedure Name:  GetSpcEnt
      // --------------------------
        dcl-proc GetSpcEnt export;
          dcl-pi *n               char(32767);
            UsrSpcName            like(SpaceName) const;
            EntNumber             bindec(9:0) value;
          end-pi;
 
      // Local Variables
          dcl-s UsrSpcPntr        pointer;
          dcl-s ListPntr          pointer;
          dcl-s Bigfield          char(32767) based(ListPntr);
          dcl-s BigfldOut         char(32767);
 
          UsrSpcPntr = GetUsrSpcP(UsrSpcName);  // Get the pointer for the user space
          ListPntr = UsrSpcPntr;                             // Move the based on pointer to get header information
          QUSH0100 = BigField;                             // Return number of list entries
 
      // Check to see if  entry requested is <= user space number entries
      // If not, return a blank field
           if EntNumber > QUSNBRLE;
             BigFldOut = *BLANKS;
             return BigFldOut;
           endif;
 
      // Return specific list entry
           EntNumber -= 1;
           ListPntr = ListPntr + QUSOLD + (QUSSEE * EntNumber);
           BigFldOut = %SUBST(BigField:1:QUSSEE);
           return BigFldOut;
        end-proc;
 
 
      // Procedure Name:  StringConvert
      // ------------------------------
        dcl-proc StringConvert export;
          dcl-pi *n               varchar(65535);
            InputData             varchar(65535) const;
            Modus                 bindec(9) value;         // 0=upper, 1=lower
          end-pi;
 
          dcl-pr ConvertCase extproc('QlgConvertCase');          // Convert upper case
            *n                    like(QLGIDRCB00);              // request
            *n                    char(65535) const options(*varsize);    // input
            *n                    char(1) options(*varsize);     // output
            *n                    int(10) const;                 // data length
            *n                    like(QUSEC)options(*nopass);   // error ds
          end-pr ;
 
       // Declarations
       /copy qsysinc/qrpglesrc,qlg
          dcl-s OutputData        char(1024);
 
          QUSBPRV = 0;                                     // use exceptions for errors
          QLGIDRCB00 = *loval;                             // set input structure to x'00'
          QLGTOR02 = 1;                                    // use CCSID for monocasing
          QLGIDOID00 = 0;                                  // use the job CCSID
          QLGCR00 = Modus;                                 // convert to upper/lower case
 
          clear OutputData;
          ConvertCase( QLGIDRCB00 :InputData :OutputData
                     :%len(%trimr(InputData)) :QUSEC);
          return %trimr(OutputData);
        end-proc; 
Achtung OS: V7R1 - TR7!