$FAB

   The $FAB macro allocates storage for a FAB and initializes
   certain FAB fields with defaults and user-specified values. No
   value is returned for this assembly-time operation.

   Format

     $FAB  ALQ=allocation-quantity,

           BKS=bucket-size,

           BLS=block-size,

           CHAN_MODE=channel-access-mode

           CTX=user-context-value,

           DEQ=extension-quantity,

           DNA=default-filespec-address,

           DNM=<filespec>,

           DNS=default-filespec-string-size,

           FAC=<BIO BRO DEL GET PUT TRN UPD>,

           FNA=filespec-string-address,

           FNM=<filespec>,

           FNS=filespec-string-size,

           FOP=<CBT CIF CTG DFW DLT MXV NAM NEF NFS OFP POS RCK RWC

           RWO SCF SPL SQO SUP TEF TMD TMP UFO WCK>,

           FSZ=header-size,

           GBC=global-buffer-count,

           LNM_MODE=logical-name-translation-access-mode,

           MRN=maximum-record-number,

           MRS=maximum-record-size,

           NAM=nam-address,

           ORG={IDX|REL|SEQ},

           RAT=<BLK{CR|FTN|PRN}>,

           RFM={FIX|STM|STMCR|STMLF|UDF|VAR|VFC},

           RTV=window-size,

           SHR=<DEL GET MSE NIL PUT UPD UPI NQL>,

           XAB=xab-address