NOVELTY - A curable composition comprises: i) an organosiloxane block copolymer containing 40 to 90 mole% disiloxy units, 10 to 60 mole% trisiloxy units, 0.5 to 35 mole% silanol groups, where disiloxy units are arranged in linear blocks having average of 10 to 400 disiloxy units, trisiloxy units are arranged in non-linear blocks having molecular weight of at least 500 g/mol and at least 30% of the non-linear blocks are crosslinked with each other, each linear block is linked to non-linear block, where block copolymer has weight average molecular weight (Mw) of at least 20000 g/mole; and stabilizer.    USE - As curable composition in solid film composition; for increasing the trouser tear strength of a solid curable film composition of a resin linear organopolysiloxane (claimed); and in light emitting diodes and solar panels.    ADVANTAGE - The film comprising the composition has a trouser tear of at least 0.75 kN/m. The solid composition has an optical transmittance of at least 95%. The stabilizer enhances the storage stability of the resin-linear organosiloxane block copolymer relative to the storage stability of a resin-linear organosiloxane block copolymer lacking a stabilizer or that has not been contacted with a stabilizer. The trouser tear strength is at least 0.5 kN/m. The trouser tear strength of the solid curable film composition is increased by at least 20% with the addition of the stabilizer, relative to solid curable film compositions lacking a stabilizer. The protecting coating comprising the composition is tough, durable, long lasting and easy to apply. The composition exhibits improved shelf stability. The composition provides coatings having optical transmission of greater than 95%.    DETAILED DESCRIPTION - A curable composition comprises: i) an organosiloxane block copolymer containing 40 to 90 mole% disiloxy units of formula ((R1)2SiO2/2), 10 to 60 mole% trisiloxy units of formula (R2SiO3/2), 0.5 to 35 mole% silanol groups (=SiOH), where the disiloxy units ((R1)2SiO2/2) are arranged in linear blocks having an average of 10 to 400 disiloxy units ((R1)2SiO2/2) per linear block, the trisiloxy units (R2SiO3/2) are arranged in non-linear blocks having a molecular weight of at least 500 g/mol, and at least 30% of the non-linear blocks are crosslinked with each other, where each linear block is linked to at least one non-linear block, and the organosiloxane block copolymer has a weight average molecular weight (Mw) of at least 20000 g/mole; and a stabilizer.    R1=1-30C hydrocarbyl;    R2=1-20C hydrocarbyl.    INDEPENDENT CLAIMS are included for the following:    (1) a process for preparing curable composition involving reacting: a) linear organosiloxane of formula (R1)q(E')(3-q)SiO((R1)2SiO2/2)nSi(E')(3-q)(R1)q and b) an organosiloxane resin comprising at least 60 mol% of (R2SiO3/2) siloxy units in its formula in an organic solvent to form a resin-linear organosiloxane block copolymer, where the amounts of (a) and (b) used in first step are selected to provide the resin-linear organosiloxane block copolymer with 40 to 90 mole% of disiloxy units ((R1)2SiO2/2) and 10 to 60 mole% of trisiloxy units (R2SiO3/2), and at least 95 weight% of the linear organosiloxane added in first step is incorporated into the resin-linear organosiloxane block copolymer; reacting the resin-linear organosiloxane block copolymer from first step to crosslink the trisiloxy units of the resin-linear organosiloxane block copolymer to increase the average molecular weight (Mw) of the resin-linear organosiloxane block copolymer by at least 50%; contacting the resin-linear organosiloxane block copolymer from second step with a stabilizer; and optionally, removing the organic solvent; and    (2) a method of increasing the trouser tear strength of a solid curable film composition of a resin linear organopolysiloxane involving adding to the composition, a stabilizer comprising an alkaline earth metal salt, a metal chelate, a boron compound, and/or silicon-containing small molecule.    n=10 to 400;    q=0, 1 or 2;    E'=hydrolyzable group containing at least one carbon atom.